UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the Securities

Exchange Act of 1934 (Amendment No.     )

1225 Old Highway 8 NW

St. Paul, Minnesota 55112

Telephone: 877-CSI-0360

Dear Stockholder:

You are cordially invited to attend the Annual Meeting of Stockholders (the “Annual Meeting”) of Cardiovascular Systems, Inc. (the “Company” or “CSI”) on Thursday,Tuesday, November 11, 2021,8, 2022, at 10:00 a.m. (Central Time). A notice of the Annual Meeting and a Proxy Statement covering the formal business of the Annual Meeting appear on the following pages.

We are excited to continue to utilize the latest technology to provide ready access, real-time communication and cost savings for our stockholders and the Company. We believe that hosting a virtual Annual Meeting will facilitate stockholder attendance and participation from any location in the world.

Whether or not you plan to attend the virtual Annual Meeting, please promptly submit your proxy by telephone or Internet or, if you received a copy of the printed proxy materials, by completing and signing the enclosed proxy card or voting instruction card and returning it in the postage-paid envelope provided. This will ensure that your shares are represented at the Annual Meeting. If you submit a proxy, you may revoke it any time before the final vote at the Annual Meeting. If you attend and wish to vote at the Annual Meeting, you will be able to do so even if you have previously submitted your proxy.

Thank you for your continued support of and interest in Cardiovascular Systems, Inc.

Sincerely,

Scott R. Ward

Chairman of the Board,

President and Chief Executive Officer

To Be Held on November 11, 20218, 2022 at 10:00 a.m. (Central Time)

These items of business are more fully described in the proxy statement accompanying this Notice.

Alexander Rosenstein

General Counsel and Corporate Secretary

September 29, 202128, 2022

You are cordially invited to attend the Annual Meeting. Whether or not you expect to attend the Annual Meeting, please submit your proxy. You may submit your proxy over the telephone or the Internet as instructed in the accompanying proxy statement. If you received a proxy card or voting instruction card by mail, you may submit your proxy or voting instructions by completing, signing, dating and mailing your proxy card or voting instruction card in the envelope provided. Any stockholder attending the Annual Meeting online may vote at the Annual Meeting, even if you already returned a proxy card or voting instruction card or submitted your proxy over the telephone or the Internet. Please note, however, that in order to vote at the Annual Meeting, you must have the 16-digit control number provided on your proxy card, voting instruction card or Notice of Internet Availability of Proxy Materials, as discussed in the accompanying proxy statement.

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE

ANNUAL MEETING TO BE HELD ON NOVEMBER 11, 2021:8, 2022:

CARDIOVASCULAR SYSTEMS, INC.

1225 Old Highway 8 NW

St. Paul, Minnesota 55112

Telephone: 877-CSI-0360

FOR THE ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD ON NOVEMBER 11, 20218, 2022

INFORMATION CONCERNING SOLICITATION AND VOTING

In accordance with rules and regulations adopted by the U.S. Securities and Exchange Commission (the “SEC”), we have elected to provide our beneficial owners and stockholders of record access to our proxy materials over the Internet. Beneficial owners are stockholders whose shares are held in the name of a broker, bank or other nominee (i.e., in “street name”). Accordingly, a Notice of Internet Availability of Proxy Materials (the “Notice”) will be mailed on or about September 29, 202128, 2022 to our beneficial owners and stockholders of record who owned our common stock at the close of business on September 14, 2021.13, 2022. Beneficial owners and stockholders of record will have the ability to access the proxy materials on a website referred to in the Notice or request a printed set of the proxy materials be sent to them by following the instructions in the Notice. Beneficial owners and stockholders of record who have previously requested to receive paper copies of our proxy materials will receive paper copies of the proxy materials instead of a Notice.

QUESTIONS AND ANSWERS ABOUT THE PROXY MATERIALS, VOTING AND PARTICIPATION IN THE ANNUAL MEETING

Why did I receive in the mail a Notice of Internet Availability of Proxy Materials instead of a full set of proxy materials?

We are pleased to take advantage of the SEC rule that allows companies to furnish their proxy materials over the Internet. Accordingly, we have sent to our beneficial owners and stockholders of record a Notice of Internet Availability of Proxy Materials. Instructions on how to access the proxy materials over the Internet or to request a paper copy may be found in the Notice. Our stockholders may request to receive proxy materials in printed form by mail or electronically by email on an ongoing basis. A stockholder’s election to receive proxy materials in printed form by mail or electronically by email will remain in effect until the stockholder terminates its election.

Why did I receive a full set of proxy materials in the mail instead of a Notice of Internet Availability of Proxy Materials?

We are providing paper copies of the proxy materials instead of a Notice to beneficial owners and stockholders of record who have previously requested to receive paper copies of our proxy materials. If you are a beneficial owner or stockholder of record who received a paper copy of the proxy materials, and you would like to reduce the environmental impact and the costs incurred by us in mailing proxy materials, you may elect to receive all future proxy materials electronically via email.

You can choose to receive our future proxy materials electronically via email by visiting www.proxyvote.com. Your choice to receive proxy materials electronically via email will remain in effect until you instruct us otherwise by following the instructions contained in your Notice and visiting www.proxyvote.com, sending an email to sendmaterial@proxyvote.com, or calling 1-800-579-1639.

The SEC has enacted rules that permit us to make available to stockholders electronic versions of the proxy materials even if the stockholder has not previously elected to receive the materials in this manner. We have chosen this option in connection with the Annual Meeting with respect to both our beneficial owners and stockholders of record.

Who can vote at the Annual Meeting?

If, on September 14, 2021,13, 2022, your shares were held, not in your name, but rather in an account at a brokerage firm, bank, dealer, or other similar organization, then you are the beneficial owner of shares held in “street name” and these proxy materials are being forwarded to you by that organization. The organization holding your account is considered to be the stockholder of record for purposes of voting at the Annual Meeting. As a beneficial owner, you have the right to direct your broker, bank or other nominee regarding how to vote the shares in your account. You are also invited to attend the virtual Annual Meeting. To vote online at the virtual Annual Meeting, you will need the 16-digit control number included with your voting instruction card or voting instructions you received from your broker, bank, or other nominee.

What am I voting on?

There are three matters scheduled for a vote:

How do I vote?

The procedures for voting are as follows:

If you are a stockholder of record, you may vote at the virtual Annual Meeting, vote by proxy using the enclosed proxy card (if you received paper copies of the proxy materials), vote by proxy over the telephone, or vote by proxy over the Internet. Whether or not you plan to attend the Annual Meeting, we urge you to submit your proxy to ensure your vote is counted. You may still attend the Annual Meeting and vote at that time even if you have already submitted your proxy.

We are providing Internet proxy voting to allow you to vote your shares via proxy online, with procedures designed to ensure the authenticity and correctness of your proxy vote instructions. However, please be aware that you must bear any costs associated with your Internet access, such as usage charges from Internet access providers and telephone companies. These costs will also apply to virtual attendance at the Annual Meeting.

How many votes do I have?

On each matter to be voted upon, you have one vote for each share of common stock you own as of September 14, 2021.13, 2022. There is no cumulative voting for election of directors.

What if I return a proxy card but do not make specific choices?

If you return a signed and dated proxy card without marking any voting selections, your shares will be voted as follows:

If any other matter is properly presented at the meeting, the persons acting as your proxies will vote your shares using their best judgment.

Who is paying for this proxy solicitation?

We will pay for the entire cost of soliciting proxies. Our directors and employees may solicit proxies in person, by telephone, or by other means of communication. Directors and employees will not be paid any additional compensation for soliciting proxies. We may also reimburse brokerage firms, banks and other agents for the cost of forwarding proxy materials to beneficial owners.

What does it mean if I receive more than one proxy card?

If you receive more than one Notice or proxy card, your shares are registered in more than one name or are held in different accounts. Please vote for each Notice and proxy card you receive to ensure that all of your shares are voted.

Are proxy materials available on the Internet?

Can I change my vote after submitting my proxy?

Yes. You can revoke your proxy at any time before the final vote at the virtual Annual Meeting. If you are the record holder of your shares, you may revoke your proxy in any one of four ways:

If your shares are held by a broker, bank or other nominee, you should follow the instructions provided by such broker, bank or other nominee.

How are votes counted?

Votes will be counted by the inspector of election appointed for the Annual Meeting, who will separately count:

Abstentions will not be counted toward the vote total for the election of directors, but abstentions will be counted towards the vote total for each other proposal, and will have the same effect as “Against” votes for those proposals. Broker non-votes have no effect and will not be counted towards the vote total for any proposal.

What are “broker non-votes”?

How many votes are needed to approve each proposal?

What is the quorum requirement?

A quorum of stockholders is necessary to hold a valid meeting. A quorum will be present if stockholders holding at least a majority of the shares outstanding sharesat the close of business on the record date are present at the virtual Annual Meeting or represented by proxy. On the record date, there were 40,581,23541,905,932 shares outstanding and entitled to vote at the Annual Meeting. Thus, the holders of 20,290,61820,952,967 shares must be present in person or represented by proxy at the Annual Meeting to have a quorum.

Your shares will be counted towards the quorum only if you submit a valid proxy (or one is submitted on your behalf by your broker, bank, or other nominee) or if you vote atattend the virtual Annual Meeting. Abstentions and broker non-votes will be counted towards the quorum requirement. If there is no quorum, the holders of a majority of shares present at the Annual Meeting in person or represented by proxy, or the chairman of the Annual Meeting, may adjourn the Annual Meeting to another date.

How can I find out the results of the voting at the Annual Meeting?

Preliminary voting results will be announced at the Annual Meeting. Final voting results will be published in a Current Report on Form 8-K, which we will file within four business days of the Annual Meeting.

When are stockholder proposals due for the fiscal 20222023 Annual Meeting?

Any appropriate proposal submitted by a stockholder and intended to be included in the Company’s proxy materials and presented at the fiscal 20222023 Annual Meeting must be submitted in writing to our Secretary at 1225 Old Highway 8 NW, St. Paul, Minnesota 55112, and received no later than June 1, 2022.May 29, 2023. A stockholder proposal to be included in the Company’s proxy materials will need to comply with the SEC regulations under Rule 14a-8 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), regarding the inclusion of stockholder proposals in company-sponsored proxy materials. Although our Board of Directors will consider stockholder proposals, we reserve the right to omit from our proxy statement a stockholder proposal that we are not required to include under the Exchange Act, including under Rule 14a-8.

Alternatively, pursuant to the advance notice provisions of the Company’s Bylaws, as authorized by applicable state law, in order for stockholders to present director nominations or other business at the fiscal 20222023 Annual Meeting without including such proposals in the Company’s proxy materials, a stockholder’s notice of such nomination or other business must be received by our Secretary at the same address no earlier than the close of business on July 14, 2022,11, 2023, and no later than the close of business on August 13, 2022,10, 2023, and must be in a form that complies with the requirements set forth in the Company’s Bylaws. You are advised to review the Company’s Bylaws for these requirements.

What are “householding” rules and how do they affect me?

The SEC has adopted rules that permit companies and brokers, banks and other nominees to satisfy the delivery requirements for proxy statements and annual reports, with respect to two or more stockholders sharing the same address and who do not participate in electronic delivery of proxy materials, by delivering a single copy of such documents addressed to those stockholders. This process, which is commonly referred to as “householding,” potentially means extra convenience for stockholders and cost savings for companies.

Brokers, banks and other nominees may be “householding” Company proxy materials. This means that only one copy of the proxy materials may have been sent to multiple stockholders in a household. If, at any time, you no longer wish to participate in householding and would prefer to receive a separate proxy statement and annual report from the other stockholder(s) sharing your address, please: (i) notify your broker, bank or other nominee, (ii) direct your written request to Investor Relations, 1225 Old Highway 8 NW, St. Paul, Minnesota 55112, or (iii) contact Investor Relations at (877) CSI-0360. The Company will undertake to deliver promptly, upon any such oral or written request, a separate copy of the proxy materials to a stockholder at a shared address to which a single copy of these documents was delivered. Stockholders who currently receive multiple copies of

Why are you holding a virtual Annual Meeting?

Our Annual Meeting will be a virtual meeting that will be conducted live via webcast. We are excited to continue to utilize the latest technology to provide ready access, real-time communication and cost savings for our stockholders and the Company. We believe that hosting a virtual meeting will more efficiently facilitate full and equal stockholder attendance and participation from any location in the world. You will bear any costs associated with your Internet access, such as usage charges from Internet access providers and telephone companies, but you will incur no costs of traveling to the meeting. A virtual Annual Meeting makes it possible for more stockholders (regardless of size, resources or physical location) to have direct access to information more quickly, while saving the Company and our stockholders time and money, especially as physical attendance at meetings has fallen. We also believe that the online tools we have selected will increase stockholder communication. We are very sensitive to concerns that virtual meetings may diminish the stockholder voice or reduce accountability of management. Accordingly, we have designed our virtual format to enhance, rather than constrain, stockholder access, participation and communication. For example, the virtual format allows stockholders to communicate with us in advance of, and during, the Annual Meeting so they can ask questions of our Board of Directors or management.

How can I participate and ask questions at the virtual Annual Meeting?

What do I do if I have technical problems during the virtual Annual Meeting?

If you encounter any difficulties accessing the virtual Annual Meeting webcast, please call the technical support number that will be posted on the Annual Meeting website log-in page.

If I am unable to participate in the live Annual Meeting webcast, can I listen to it later?

An audio replay of the Annual Meeting and a written transcript of the Annual Meeting, including the questions answered during the Annual Meeting, will be available as soon as practical on www.csi360.com, and will remain posted until our fiscal 20222023 Annual Meeting (that is, the meeting we currently expect to hold in November 2022)2023).

PROPOSAL 1

ELECTION OF DIRECTORS

Our Board of Directors (the “Board”) is divided into three classes, with each class serving staggered three-year terms. Vacancies on the Board may be filled only by persons elected by a majority of the remaining directors. A director elected by the Board to fill a vacancy in a class, including vacancies created by an increase in the number of directors, will serve for the remainder of the full term of that class and until such director’s successor is elected and qualified.

Directors are elected by a majority of the votes cast in uncontested elections. The election of directors at the Annual Meeting will be uncontested. Under the majority voting standard, a nominee must receive a number of “For” votes that exceeds 50% of the votes cast with respect to that nominee’s election. Votes cast with respect to a nominee include votes “For” or “Against” a nominee and exclude abstentions and broker non-votes. In a contested election, directors will be elected by a plurality vote. A contested election is an election in which the number of candidates for election as directors exceeds the number of directors to be elected. Under the plurality standard, the nominees receiving the greatest number of “For” votes (among votes properly cast in person or by proxy) will be elected as directors.

If an uncontested nominee for director does not receive a majority of “For” votes, he or she, if a current director, is required to offer to resign from the Board. The Governance/Nominating Committee and the Board will then determine whether the offered resignation should be accepted or rejected, and they may consider any factors they deem relevant in deciding whether to accept the resignation. The Board will publicly disclose its decision regarding the offered resignation within 90 days after the election results have been certified. Any director who has so offered his or her resignation will not be permitted to vote on or participate in the decision regarding that resignation. If an uncontested nominee for director who is not a current director does not receive a majority of “For” votes, he or she will not be elected to the Board.

Unless a contrary choice is specified, shares represented by executed proxies will be voted “For” the election of the nominees named in this proxy statement, or, if a nominee becomes unavailable for election as a result of an unexpected occurrence, “For” the election of a substitute nominee designated by our Board. The nominees have agreed to serve as a director if elected, and we have no reason to believe that any of the nominees will be unable to serve.

NOMINEES FOR ELECTION FOR A THREE-YEAR TERM EXPIRING AT THE FISCAL 2025 ANNUAL MEETING

DIRECTORS CONTINUING IN OFFICE UNTIL THE FISCAL 2024 ANNUAL MEETING

DIRECTORS CONTINUING IN OFFICE UNTIL THE FISCAL 2023 ANNUAL MEETING

INFORMATION REGARDING THE BOARD OF DIRECTORS AND CORPORATE GOVERNANCE

INDEPENDENCE OF THE BOARD OF DIRECTORS

Under the Nasdaq Stock Market (“Nasdaq”) listing standards, a majority of the members of a listed company’s board of directors must qualify as “independent,” as affirmatively determined by the board of directors. Our Board consults with the Company’s legal counsel to ensure that the Board’s determinations are consistent with relevant securities and other laws and regulations regarding the definition of “independent,” including those set forth in the applicable Nasdaq listing standards as in effect from time to time.

Consistent with these considerations, the Board, following the determination of the Governance/Nominating Committee, has affirmatively determined that the following directors are independent within the meaning of the applicable Nasdaq listing standards: Messrs. Brown, Lawlor, Paulsen, Stenbeck, and Womack, Ms. Aronson, and Drs. Cohn and Jain. In making this determination, the Board and the Governance/Nominating Committee reviewed whether there were any relevant transactions or relationships between each director, nominee, or any of his or her family members, and the Company, its senior management and its independent registered public accounting firm, and determined that there were none.

In making its determination as to the independence of the above-listed directors, the Board found that none of these directors had a material or other disqualifying relationship with the Company. Mr. Ward, the Company’s President and Chief Executive Officer, is not an independent director by virtue of his service as an officer of the Company.

BOARD LEADERSHIP STRUCTURE

Prior to August 2016, we had separate individuals serving as Chairman of the Board and as President and Chief Executive Officer. However, in connection with the appointment of Mr. Ward to serve as our President and Chief Executive Officer in August 2016, the Board gave thoughtful and rigorous consideration to its governance structure and determined at that time that having the same individual serve as the President and Chief Executive Officer and as the Chairman of the Board best serves the interests of the Company and our stockholders. The Board believes that Mr. Ward’s extensive knowledge of, and experience in, the medical device industry will allowallows him to provide focused, long-term leadership and direction for the Board and executive management. As the President and Chief Executive Officer, Mr. Ward is additionally responsible for setting the strategic direction of the Company and managing the day-to-day leadership and performance of the Company. The combined roles provide clear accountability on both short- and long-term goals and a single focus for the Company’s long-term growth.

Additionally, because we believe independent directors and management have different perspectives and roles in strategy development, the Board appointed Edward Brown as Lead Independent Director when Mr. Ward was appointed to serve as our President and Chief Executive Officer. AsUpon the completion of Mr. Brown will no longer be a director following the Annual Meeting,Brown’s service on the Board intendsin November 2021, the Board appointed Augustine Lawlor to appoint a new Lead Independent Director to replacesucceed Mr. Brown as of the time of the expiration of his term.Lead Independent Director.

The Lead Independent Director has the following responsibilities:

The Lead Independent Director promotes active participation of the independent directors and strengthens the role of the Board in fulfilling its oversight responsibility and fiduciary duties to our stockholders.

OVERSIGHT OF RISK MANAGEMENT

CODE OF ETHICS AND BUSINESS CONDUCT

The Company has adopted the Cardiovascular Systems, Inc. Code of Ethics and Business Conduct, which applies to all officers, directors and employees and was last amended on JulySeptember 1, 2019.2022. We intend to maintain the highest standards of ethical business practices and compliance with all laws and regulations applicable to our business. The Code of Ethics and Business Conduct, as amended, is available on our website at www.csi360.com in the “Corporate Governance” section. We intend to satisfy the disclosure requirement under Item 5.05 of Form 8-K regarding an amendment to, or waiver from, a provision of our Code of Ethics and Business Conduct by either posting such information on our website at the web address and location specified above or filing a Form 8-K.

STOCKHOLDER COMMUNICATIONS WITH THE BOARD OF DIRECTORS

Stockholders may communicate directly with the Board. All communications should be directed to the Company’s Secretary at the address below and should prominently indicate on the outside of the envelope that it is intended for the Board or for non-management directors, and the Company’s Secretary will forward the communications to all specified directors. If no director is specified, the communication will be forwarded to the entire Board. Stockholder communications to the Board should be sent to:

DIRECTOR ATTENDANCE AT ANNUAL MEETINGS OF STOCKHOLDERS

Directors’ attendance at annual meetings of our stockholders can provide stockholders with an opportunity to communicate with directors about issues affecting the Company. We encourage, but do not require, our directors and nominees for director to attend annual meetings of stockholders. All of our then-currentcurrent directors attended our last annual meeting of stockholders, held on November 11, 2020.2021.

MEETINGS OF THE BOARD OF DIRECTORS

INFORMATION REGARDING COMMITTEES OF THE BOARD OF DIRECTORS

Below is a description of each committee of the Board as such committees are presently constituted. The Board has determined that each current member of each committee meets the applicable SEC and Nasdaq rules and regulations regarding “independence” and that each member is free of any relationship that would impair his or her individual exercise of independent judgment with regard to the Company.

Audit, Risk Management and Finance Committee

Our independent registered public accounting firm, legal counsel and management periodically meet privately with our Audit Committee.

Each Audit Committee member is a non-employee director of our Board. The Board reviews the Nasdaq listing standards definition of independence for Audit Committee members on an annual basis and has determined that all current members of the Company’s Audit Committee are independent (as independence is currently defined in Rule 5605(a)(2) of the Nasdaq listing standards and Rule 10A-3(b)(1) under the Exchange Act).

Audit Committee Financial Expert

The Board has determined that Mr. Stenbeck is the “audit committee financial expert,” as defined in Item 407(d)(5)(ii) of Regulation S-K, as amended. As noted above, Mr. Stenbeck is independent within the meaning of Nasdaq’s listing standards. The designation of Mr. Stenbeck as the audit committee financial expert does not impose on Mr. Stenbeck any duties, obligations or liability that are greater than the duties, obligations and liability imposed on Mr. Stenbeck as a member of the Audit Committee and the Board in the absence of such designation.

Report of the Audit Committee of the Board of Directors

In accordance with its written charter, the Audit Committee assists the Board with fulfilling its oversight responsibility regarding the quality and integrity of the accounting, auditing and financial reporting practices of the Company. In discharging its oversight responsibilities regarding the audit process, the Audit Committee:

Audit, Risk Management and Finance Committee of the Board of Directors:

Stephen Stenbeck, Chair

Martha Goldberg Aronson

Human Resources and Compensation Committee

Our Human Resources and Compensation Committee (the “Compensation Committee”) consists of four directors: Martha Goldberg Aronson, Chair, Augustine Lawlor, Erik Paulsen and Kelvin Womack. All members of the Company’s Compensation Committee were appointed by the Board, and the Compensation Committee consists entirely of directors who are “non-employee directors” for purposes of Rule 16b-3 under the Exchange Act, and “independent,” as independence is currently defined in Rule 5605(a)(2) of the Nasdaq listing standards.

The Compensation Committee thoroughly reviewed Willis Towers Watson relative to the six independence factors highlighted by the SEC and has concluded that Willis Towers Watson is independent.

Compensation Committee Interlocks and Insider Participation

As indicated above, the Compensation Committee consists of Ms. Aronson and Messrs. Lawlor, Paulsen and Womack. No member of the Compensation Committee has ever been an executive officer or employee of ours. None of our officers currently serves, or has served during the last completed year, on the compensation committee or the board of directors of any other entity that has one or more officers serving as a member of the Board or the Compensation Committee.

Governance/Nominating Committee

Our Governance/Nominating Committee consists of three directors: Edward Brown,Augustine Lawlor, Chair, William Cohn, and Erik Paulsen. Edward Brown was Chair until November 11, 2021. All members of the Company’s Governance/Nominating Committee are “independent,” as independence is currently defined in Rule 5605(a)(2) of the Nasdaq listing standards.

The Governance/Nominating Committee considers the following skills and characteristics in the matrix referenced above, all of which are represented by members of our Board:

Board of Directors Qualifications and Diversity

In the case of incumbent directors whose terms of office are set to expire, the Governance/Nominating Committee reviews their overall service to the Company during their terms, including the number of meetings attended, level of participation, quality of performance, and any other relationships and transactions that might impair the directors’ independence. In the case of new director candidates, the Governance/Nominating Committee also determines whether the nominee is independent for Nasdaq purposes, which determination is based upon applicable Nasdaq listing standards, applicable SEC rules and regulations and the advice of counsel, if necessary. The Governance/Nominating Committee conducts any appropriate and necessary inquiries into the backgrounds and qualifications of possible candidates after considering the function and needs of the Board. The Governance/Nominating Committee meets to discuss and consider the candidates’ qualifications and then selects a nominee by majority vote.

The Governance/Nominating Committee will consider director candidates recommended by business and professional sources, including executive search firms, and director candidates recommended by stockholders. The Governance/Nominating Committee intends to evaluate all director candidates in the same manner, including the minimum criteria set forth above, whether or not the candidate was recommended by a stockholder. To nominate a director for the fiscal 20222023 Annual Meeting, stockholders must submit such nomination in writing to our Secretary at 1225 Old Highway 8 NW, St. Paul, Minnesota 55112 not later than the close of business on August 13, 2022,12, 2023, nor earlier than the close of business on July 14, 2022;13, 2023; provided, however, that in the event that the date of the fiscal 20222023 annual meeting changes more than 30 days from November 11, 2022,8, 2023, the written proposal must be delivered not earlier than the close of business on the 120th day prior to the date of the fiscal 20222023 Annual Meeting and not later than the close of business on the later of the 90th day prior to the date of the fiscal 20222023 Annual Meeting or the 10th day following the day on which public announcement of the date of the fiscal 20222023 Annual Meeting is first made by the Company. You are advised to review the Company’s Bylaws for requirements relating to director nominees.

As described in our Code of Ethics and Business Conduct, our company is mission-driven, patient-centric and customer focused. Our mission is Saving Limbs. Saving Lives. Every Day. Patients are at the center of everything we do, as we lead the

way in the effort to successfully treat arterial calcium, a common complication for millions of patients suffering from peripheral

and coronary artery diseases, by developing innovative medical devices to help us fulfill our mission. Our core values of Accountability, Community, Courage, Excellence, Integrity and Velocity guide the work we do every day and are used in our

VOTE REQUIRED

PROPOSAL 2

RATIFICATION OF APPOINTMENT OF INDEPENDENT AUDITORS

The Audit Committee has appointed PricewaterhouseCoopers LLP as the Company’s independent registered public accounting firm for the fiscal year ending June 30, 2022,2023, and the Board has directed that the appointment of the independent registered public accounting firm be submitted for ratification by the stockholders at the Annual Meeting. PricewaterhouseCoopers LLP also served as the Company’s independent registered public accounting firm for the fiscal year ended June 30, 20212022 and has been the Company’s independent registered public accounting firm since February 25, 2009. Representatives of PricewaterhouseCoopers LLP are expected to be present at the Annual Meeting. They will have an opportunity to make a statement if they so desire and will be available to respond to appropriate questions.

The Audit Committee is directly responsible for the appointment, compensation (including the negotiations therefor), retention and oversight of PricewaterhouseCoopers LLP. The Audit Committee and its Chair are directly involved in the selection of the lead engagement partner of PricewaterhouseCoopers LLP when there is a required rotation. While the Audit Committee periodically considers whether there should be a regular rotation of the Company’s independent auditors, members of the Audit Committee and the Board believe that the continued retention of PricewaterhouseCoopers LLP as the Company’s independent registered public accounting firm is in the best interests of the Company and its stockholders.

Neither the Company’s Bylaws nor other governing documents or law require stockholder ratification of the appointment of PricewaterhouseCoopers LLP as the Company’s independent registered public accounting firm. However, the appointment of PricewaterhouseCoopers LLP is being submitted to the stockholders for ratification as a matter of good corporate practice. If the stockholders fail to ratify the appointment, the Audit Committee will reconsider whether or not to retain PricewaterhouseCoopers LLP. Even if the appointment is ratified, the Audit Committee inat its discretion may direct the appointment of different independent auditors at any time during the year if it determines that such a change would be in the best interests of the Company and its stockholders.

PRINCIPAL ACCOUNTANT FEES AND SERVICES

In connection with the audit of the fiscal 20212022 financial statements, the Company entered into an engagement agreement with PricewaterhouseCoopers LLP that setsset forth the terms by which PricewaterhouseCoopers LLP performed audit services for the Company.

PRE-APPROVAL POLICIES AND PROCEDURES

Pursuant to its written charter, the Audit Committee is required to pre-approve the audit and non-audit services performed by our independent auditors. The Audit Committee may not approve non-audit services prohibited by applicable regulations of the SEC if such services are to be provided contemporaneously while serving as independent auditors. The Audit Committee has delegated authority to the Chair of the Audit Committee to approve the commencement of permissible non-audit related services to be performed by the independent auditors and the fees payable for such services, provided that the full Audit Committee subsequently ratifies and approves all such services. For fiscal 2021,2022, all audit and non-audit services performed by our independent auditors were pre-approved in accordance with such pre-approval policies. The Audit Committee has determined that the rendering of the services other than audit services by PricewaterhouseCoopers LLP is compatible with maintaining the principal accountant’s independence.

VOTE REQUIRED

EXECUTIVE COMPENSATION

Compensation Discussion and Analysis

Executive Summary

Say on Pay Results and Stockholder Engagement

Overview of Compensation and Process

The Compensation Committee worked with management and with our independent compensation consultant, Willis Towers Watson, to design the executive compensation programs for fiscal 2021,2022, following the belief that compensation should reflect the value created for the stockholders while furthering the Company’s strategic goals. In doing so, we instituted our compensation programs to achieve the following goals:

These objectives emphasize pay for performance by structuring the compensation elements such that a higher percentage of compensation is variable based upon Company performance.

The compensation package for each executive officer is comprised of the three elements set forth in the table below:

The following graphs illustrate the relative percentages of these elements at target for each of the Named Executive Officers for fiscal 2021:2022:

Our Compensation Committee, in consultation with its independent compensation consultant, Willis Towers Watson, administers our compensation program for the Named Executive Officers. The Compensation Committee regularly invites a representative of its independent compensation consultant to participate in Compensation Committee meetings and seeks the consultant’s views regarding various compensation related issues. In connection with the annual review of executive officer and director compensation, at the request of the Compensation Committee, this consultant provides the Committee with data regarding the compensation paid to executive officers and directors of companies deemed to be comparable to us (the “Compensation Peer Group”).

In establishing relevant peers that are similar to us, the Compensation Committee considered several factors, namely: companies in the healthcare equipment industry with an emphasis on research and development, companies with similar financial scope (e.g., revenue, EBITDA and market capitalization), and companies with a significant sales force. The Compensation Committee believes that the companies listed below generally meet some or all of these criteria.

In making compensation decisions, the Compensation Committee compares all elements of total compensation to the companies in the Compensation Peer Group. The Compensation Committee reviews the compensation paid to executives in the Compensation Peer Group and performance evaluations presented by management in determining the appropriate aggregate and

individual compensation levels for the performance year. In conducting its review, the Compensation Committee considers quantitative performance results of the Company and the overall need of the Company to attract, retain and motivate the executive team.

The following table summarizes best practices that we follow and practices that we avoid in establishing our executive compensation program:

Base Salaries

Base salary is an important element of our executive compensation program as it provides executives with a competitive, fixed, non-contingent earnings stream to support annual living and other expenses. As a component of total compensation, we generally target base salaries at the median of Compensation Peer Group salaries for comparable positions, a level that we believe is sufficient to attract and retain an experienced management team that will successfully grow our business and create stockholder value. Base salaries are reviewed regularly and adjusted to reward individual performance and contributions to our overall business objectives. We seek to do so in a manner that does not detract from the executives’ incentive to realize additional compensation through our performance-based compensation programs.

The Compensation Committee reviews the Chief Executive Officer’s base salary annually at the end of each fiscal year. The Compensation Committee may recommend that the Board make adjustments to the Chief Executive Officer’s base salary based upon the Compensation Committee’s review of his current base salary, incentive cash compensation and equity-based compensation, as well as his performance and comparative market data. The Compensation Committee reviews other executives’ base salaries at the end of each fiscal year, with input from the Chief Executive Officer. The Compensation Committee may approve adjustments to other executives’ base salary based upon the Chief Executive Officer’s

In utilizing comparative data, the Compensation Committee seeks to approve or recommend to the Board, as the case may be, salaries for each executive at a level that is appropriate after giving consideration to experience for the relevant position and the executive’s performance. The Compensation Committee reviews performance for both the Company (based upon achievement of strategic initiatives) and each individual executive. Based upon these factors, the Compensation Committee may approve or recommend to the Board, as the case may be, adjustments to base salaries to better align individual compensation with

comparative market compensation, to provide merit-based increases based upon individual or Company achievement, or to account for changes in roles and responsibilities.

Annual Incentive

Each Named Executive Officer has a target annual cash incentive that is a percentage of his or her base salary. In fiscal 2021,2022, target incentive levels as a percentage of base salary were:

The Compensation Committee structures the Company’s annual cash incentive program to reward its Named Executive Officers based on the Company’s fiscal year performance. Each year, after the Company’s annual financial planning process, the Compensation Committee and the Board establish the financial objectives that need to be achieved by the Company for the Named Executive Officers to earn the cash incentive. These financial objectives vary from year to year, depending on the Company’s business goals.

When aggregating the financial results for eachthe third and fourth quarters of fiscal quarter2022 and the adjustments to adjusted EBITDA described above, the actual achievement by measure was 89.0%82.7% of the quarterly revenue targets and 129.9%86.6% of the quarterly adjusted EBITDA targets, resulting in an overall total payout of 99.2% under the Fiscal 2021 Annual Incentive Plan.second half plan of 83.7% of target (which was equal to 41.8% of the target under the full year plan).

Discretionary Bonuses

Long-Term Incentives

We provide long-term incentives to the Named Executive Officers through grants of equity. Under our Amended and Restated 2017 Equity Incentive Plan (the “2017 Plan”), we may make grants of restricted stock awards, stock options, restricted stock units, performance share awards, performance unit awards and stock appreciation rights to officers and other employees. We adopted the 2017 Plan and our prior equity incentive plans to give us flexibility in the types of awards that we could grant to our executive officers and other employees in order to meet our business needs. In fiscal 2021,2022, we used equity awards to emphasize performance, stockholder alignment and retention.

In fiscal 2021,2022, the Compensation Committee approved equity grants to the Named Executive Officers, other than Mr. Ward, and recommended to the Board for approval equity grants to Mr. Ward. In each case, the Compensation Committee or the Board, as applicable, approved an aggregate dollar amount of equity for each Named Executive Officer, which awards were granted in the share amounts set forth in the table below based on the closing price of our common stock on August 7, 2020.9, 2021.

Each Named Executive Officer has a target equity incentive expressed as a percentage of his or her base salary. In fiscal 2021,2022, target equity incentive levels as a percentage of base salaries were:

The value was then split to provide 60% of the value in performance-based restricted stock, which vests based on target level performance, and 40% in time-based restricted stock in order to more heavily align these incentives with performance and stakeholder interests.

For fiscal 2021,2022, the Board and the Compensation Committee determined that the performance-based restricted stock would vest entirely based on total stockholder return and the measurement period would be three years, in each case in order to align executive incentives with long-term stockholder interests. Accordingly, the performance-based restricted stock granted in fiscal 20212022 will vest based on our total stockholder return relative to total stockholder return of the Compensation Peer Group, as measured by the closing prices of our stock and the Compensation Peer Group members for the 90 trading days preceding July 1, 20202021 compared to the closing prices of our stock and the Compensation Peer Group members for the 90 trading days preceding July 1, 2023,2024, as follows:

Vesting of the performance-based restricted stock will occur on the date that our Annual Report on Form 10-K for the fiscal year ending June 30, 20232024 is filed.

The performance-based restricted stock was granted to each Named Executive Officer at the maximum number of shares that could be earned, which is 200% of the target number of shares allocated to performance-based restricted stock. Any shares not earned will be forfeited upon confirmation of the performance level actually achieved.

(1) The award vests as to one-third of the shares at each of the first three anniversaries of August 13, 2020.2021.

(2) The award vests as to one-half of the shares at each of the first two anniversaries of February 12, 2022.

If an executive officer holds restricted stock with time-based vesting, and his or her employment is terminated for any reason (other than change of control or events under the Severance Plan), including death or disability, prior to restrictions lapsing, all of the executive officer’s rights to all of the shares subject to forfeiture are immediately and irrevocably forfeited. If an executive officer holds restricted stock with total stockholder return conditions on vesting, and his or her employment is terminated for any reason (other than change of control or events under the Severance Plan), including death or disability but not including termination for cause, prior to the total stockholder return criteria being satisfied, he or she will forfeit a pro rata portion of the shares subject to the award based on the number of months in the three-year performance period remaining following termination.

The general policy of the Company is to grant restricted stock to executives at the first Board meeting of the fiscal year, with the effective date of the grant being the third business day following the Company’s fiscal year-end earnings release or a later date if the first Board meeting is held after the date of the earnings release or if an executive joins the Company later in the fiscal year. The number of shares granted is based on a formula that sets an incentive compensation amount as the percentage of

Stock Ownership Guidelines and Certain Restrictions on Stock Ownership

On August 18, 2014, the Board established minimum stock ownership guidelines for our executive officers. These guidelines require executive officers to hold shares of the Company’s common stock with the following values:

Each current officer has five years from such person’s original date of appointment to his or her current position, and any new officer appointed will have five years from the date of such person’s appointment, to reach the applicable ownership level. For purposes of these guidelines, unvested time-based restricted stock awards will count toward such ownership level but unvested performance-based restricted stock awards will not count toward such ownership level. The Compensation Committee is

authorized to administer such guidelines, including the authority to make such guidelines applicable to other officers of the Company and resolve any questions of interpretation or application. The Board believes that stock ownership by executive officers is important to align their interests more closely with those of stockholders.

Under our Insider Trading Policy, executive officers and other employees may not pledge or sell short Company stock, and they are prohibited from engaging in hedging or monetization transactions with respect to their Company stock. All of our executive officers are in compliance with these guidelines.

Limited Perquisites; Other Benefits

Nonqualified Deferred Compensation Plans

We maintain the Cardiovascular Systems, Inc. Deferred Compensation Plan (the “Deferred Compensation Plan”) to provide benefits to a select group of management or highly compensated employees who contribute materially to the continued growth, development and future business success of the Company, including the Named Executive Officers. The Compensation Committee administers the Deferred Compensation Plan.

For deferrals of base salary, participants must make their elections by the end of the calendar year that precedes the calendar year within which the base salary will be earned. For deferrals of performance bonus, subject to certain exceptions, participants must make their elections by the end of the calendar year prior to the year in which the performance bonus is earned. For deferrals of discretionary bonus, participants must make their elections by the end of the calendar year preceding the fiscal year in which the performance period commences.

Each participant may, at the time of his or her deferral election, choose to allocate the deferred compensation into certain categories of hypothetical investments as determined by the Compensation Committee. The Compensation Committee offers two alternatives, the first with a fixed income and the second with a return equal to that of the equal-weighted Standard & Poor’s 500 stock index. The amount payable to each participant under the Deferred Compensation Plan will change in value based upon the hypothetical investment selected by that participant.

Each participant, in connection with his or her commencement of participation in the Deferred Compensation Plan, is required to irrevocably elect whether to (i) accelerate the payment of his or her deferred compensation in the event of a change in control of the Company or (ii) have his or her deferred compensation remain in the Deferred Compensation Plan and paid pursuant to the terms and conditions of the Deferred Compensation Plan in the event of a change in control of the Company.

In the event of an unforeseen emergency, participants may apply to accelerate payment of the deferred compensation to the extent reasonably needed to satisfy the financial hardship resulting from the emergency.

The accounts established for participants in the Deferred Compensation Plan will be unfunded and the right of any participant to receive a distribution under the Deferred Compensation Plan will be an unsecured claim against the general assets of the Company. No participant in the Deferred Compensation Plan will have any rights in or against any specific assets, fund, trust or account of the Company.

Compensation Consultant

In preparation for fiscal 2021,2022, the Compensation Committee engaged Willis Towers Watson, a third-party compensation consulting firm, to advise the Compensation Committee in connection with its determination of competitive compensation levels for our executive officers, including base salary, annual incentive compensation, and equity-based compensation.

Termination or Change of Control Plans and Agreements

The majority of our equity incentive agreements provide that in the event of a change of control (defined in such agreements as the sale by us of substantially all of our assets and the consequent discontinuation of our business, or a merger, exchange or liquidation), the vesting of all equity grants at their full outstanding unvested levels will automatically accelerate. Accordingly, restricted stock (including both the time-based and performance-based restricted stock) will immediately vest as of the effective date of a change of control.

Under the terms of our employment agreements with Messrs. Ward and Points, and Ms. Robb, we will pay such officer the number of months of base salary and our share of health insurance costs set forth below if they are terminated by us without “cause” or if they terminate their employment for “good reason” (each as defined in the respective agreement).

Messrs. Ward and Points and Ms. Robb will also receive a pro rata portion of any performance bonus for which the performance period has not expired. If such officer is terminated by us without “cause” or if he or she terminates his or her employment for “good reason” within 24 months of a change of control, the base salary payable during the applicable severance period will be increased to include the officer’s target bonus for the year of termination. As a condition to receiving the severance benefits, each officer is required to execute a release of claims agreement in favor of the Company. The severance benefits under their employment agreements and the Severance Plan are substantially the same; however, the Severance Plan does not provide severance benefits for an officer who terminates employment for “good reason” outside of the change of control context.

We maintain the Cardiovascular Systems, Inc. Executive Officer Severance Plan (as amended, the “Severance Plan”). Each of our Named Executive Officers is covered by the Severance Plan. Under the Severance Plan, if we terminate an executive officer other than for cause, as defined in the Severance Plan, the executive will receive certain severance benefits during the severance period. The severance period is 24 months for the Chief Executive Officer, 18 months for all officers (within the meaning of Section 16 of the Exchange Act); 15 months for Senior Vice Presidents and Executive Vice Presidents; 12 months for Vice Presidents and other corporate officers; and 6 months or another period designed by the Compensation Committee for Area Vice Presidents and other employees designated by the Compensation Committee. For purposes of the Severance Plan, “cause” is generally defined as the executive’s (i) failure to perform his or her material duties; (ii) willful or deliberate misconduct; (iii) false or materially misleading representation made to the Board; or (iv) commission of any felony. The severance benefits generally consist of the continued payment of (i) the executive’s then-current base salary; and (ii) our share of the costs of the executive’s coverage under our medical, dental, and life insurance plans. In addition, the Board or Compensation Committee must take action to provide for the acceleration of the vesting for any outstanding stock options, restricted stock awards, restricted stock unit awards or other equity awards previously granted to the executive that would have vested within the 12-month period immediately following the executive’s termination of employment, and permit any outstanding stock options to remain exercisable for 180 days following the executive’s termination of employment. The Severance Plan also provides that, in the event of the participant’s termination within 24 months following a change in control (the sale by us of substantially all of our assets and the consequent discontinuance of our business; a merger, exchange, liquidation or certain acquisitions; certain changes in the composition of the Board; or a definitive agreement relating to any of these), the base salary payable during the applicable severance period will be increased to include the participant’s target bonus for the year of termination. In addition, if a participant in the Severance Plan resigns his or her employment for “good reason” within 24 months of a change of control, then that participant is entitled to the same payments as if such participant’s employment is terminated without cause, for the same severance period previously set forth in the Severance Plan. For purposes of the Severance Plan, “good reason” is generally defined as (i) a material diminution in an executive’s base salary; (ii) a material diminution in the executive’s authority, duties or responsibilities; (iii) a material diminution in the authority, duties, or responsibilities of the supervisor to

whom the executive reports; (iv) a material diminution in the budget over which the executive retains authority; (v) requiring executive to be based at a location that is more than 50 miles from the location of the executive’s principal office; (vi) our failure to provide the executive with the same target bonus opportunity as in effect prior to the change in control; (vii) our failure to provide the executive with employee benefit plans that provide substantially similar benefits in the aggregate as the benefits provided to the executive immediately prior to a change of control; or (viii) any other action or inaction that constitutes a material breach by us of any agreement under which the executive provides services.

As a condition to receiving these severance benefits, the executive is required to execute a release of claims agreement in favor of the Company. The executive is not entitled to severance benefits if his or her termination is due to death or disability; if the executive is on military leave, sick leave, or another bona fide leave of absence generally not exceeding six months; or if the executive continues to provide services to us in excess of 20% of the average level of services that he or she performed over the immediately preceding 36-month period.

The Severance Plan does not affect any other rights our executives may have to severance benefits in their employment agreements. However, an executive will be eligible for severance benefits under the Severance Plan only to the extent the severance is not duplicative of the benefits received by the executive under his or her employment agreement. The executive will receive benefits under his or her employment agreement first, and then will be eligible for severance benefits under the Severance Plan; provided, however, that the combined benefit will not exceed the maximum benefit available under the Severance Plan.

Although we have the right to amend or terminate the Severance Plan, we may not do so in any manner that diminishes the severance benefits (i) within 24 months of a change of control; (ii) if such amendment or termination was requested by a party other than the Board that had previously taken other steps reasonably calculated to result in a change of control and that ultimately resulted in a change of control; or (iii) if such amendment or termination arose in connection with or in anticipation of a change of control that ultimately occurs.

As noted above, participants in the Deferred Compensation Plan are required to irrevocably elect whether to (i) accelerate the payment of his or her deferred compensation in the event of a change in control of the Company or (ii) have his or her deferred compensation remain in the Deferred Compensation Plan and paid pursuant to the terms and conditions of the Deferred Compensation Plan in the event of a change in control of the Company. None of our current Named Executive Officers have elected to participate in the Deferred Compensation Plan.

Compliance with Internal Revenue Code Section 162(m)

As a result of Section 162(m) of the Internal Revenue Code of 1986, as amended, we will not be allowed a federal income tax deduction for compensation paid to certain executive officers to the extent that compensation exceeds $1 million per officer in any one year. This limitation applies to all compensation paid to the Named Executive Officers.

The Compensation Committee believes that factors other than tax deductibility are important in the design of executive compensation programs and that it is important to preserve flexibility in compensating our executive officers in a manner that can best promote our corporate objectives. Our Compensation Committee intends to continue to compensate our executive officers in a manner consistent with the best interests of the Company and our stockholders.

Human Resources and Compensation Committee Report

The Human Resources and Compensation Committee has reviewed and discussed the Compensation Discussion and Analysis with management. Based upon this review and discussion, the Human Resources and Compensation Committee recommended to the Board of Directors that the Compensation Discussion and Analysis be included in this proxy statement and in our Annual Report on Form 10-K for the fiscal year ended June 30, 2021.2022.

Human Resources and Compensation Committee of the Board of Directors:

Augustine Lawlor

Erik Paulsen

Kelvin Womack

Summary Compensation Table for Fiscal 20212022

Grants of Plan-Based Awards for Fiscal 20212022