Exhibit 10.4

February 6, 2018

Via Hand Delivery

To:    Larry Betterley

Re:    Transition Agreement

Dear Larry:

As you know, you have indicated to Cardiovascular Systems, Inc. (“CSI”) that you
plan to voluntarily resign your employment with CSI for the purpose of
retirement effective August 15, 2018. The purpose of this letter agreement is to
confirm your and CSI’s agreement with regard to the upcoming transition and end
of your employment relationship with CSI. As used herein, the “Transition
Period” shall be the period commencing as of the date you sign this letter
agreement below and ending at the close of business on August 15, 2018.

Through February 6, 2018, you will remain employed in your current role of Chief
Financial Officer under your current terms and conditions of employment.
Effective at the close of business on February 6, 2018, you will automatically
be deemed to have voluntarily resigned from your position as an executive
officer of CSI, but you will remain employed by CSI. At that time, you will no
longer be eligible for CSI’s CSI Executive Officer Severance Plan as restated
November 15, 2017 (the “Plan”); instead, you will be offered the Severance
Package summarized below. Notwithstanding the foregoing, if CSI terminates your
employment without Cause (including due to Reduction-In-Force) or you resign for
Good Reason, as those terms are defined in the Plan, prior to August 15, 2018,
CSI will offer you a severance package equal to what you would have been offered
under such Plan as a Section 16 Officer and the terms of this letter agreement
will be null and void.

Effective February 7, 2018, pursuant to your written consent as indicated by
your signature below, you will assume a new position of Vice President,
Administration and your current pay (annualized salary of $379,212) and employee
benefits will remain in place. Your annual bonus eligibility for FY18 (July 1,
2017 - June 30, 2018) will remain in place unchanged per the terms and
conditions of the applicable bonus plan. You will not be eligible to earn or
receive any bonus pay for the period commencing July 1, 2018 and thereafter.

Your employment with CSI will end on August 15, 2018 as a result of your
voluntary resignation due to retirement. As of August 15, 2018, CSI will offer
you a severance package consisting of (1) a one-year consulting agreement
commencing August 16, 2018 and ending August 15, 2019 (unless terminated earlier
as set forth in such agreement) under which you will be paid $3,333 per month,
provided, however, that in no event shall such consulting services be greater
than 16 hours per month (which is less than twenty percent (20%) of the level of
services performed by you over the 36-month period ending on August 15, 2018),
(2) allowing your time-based restricted stock awards to continue to vest through
August 15, 2019, (3) allowing your two performance-based restricted stock awards
to continue to vest through their respective vesting periods (provided, that the
performance criteria for such vesting are met as determined by CSI in accordance
with the terms for such restricted stock (in or around August or September 2019
and 2020 (as applicable)) such that, if and to the extent applicable, such
shares will vest as of such determination), and (4) paying COBRA premiums for
you and your eligible dependents for up to 18 months or, if earlier, such time
as you or your eligible dependents are eligible for other health insurance
coverage (collectively, the “Severance

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Package”). Your receipt of the Severance Package is conditioned upon your
remaining in compliance with any restrictive covenant agreements you have with
CSI, including those set forth in Sections 9-13 of your Employment Agreement
with CSI dated April 7, 2008 (as amended, your “Employment Agreement”), and you
executing, not rescinding and complying with a full and final release of claims
agreement in favor of CSI in a form supplied by CSI, to include other standard
terms such as cooperation, non-disparagement and confidentiality (the
“Separation Agreement”). The Separation Agreement and the consulting agreement
will be provided to you on or about August 15, 2018 for your signature.
 
Notwithstanding anything herein to the contrary, during the Transition Period,
you will remain employed on an at-will basis as provided in Section 8.1 of your
Employment Agreement. As noted above, if your employment is terminated by CSI
without Cause (including due to Reduction-In-Force) or you resign for Good
Reason, as those terms are defined in the Plan, prior to August 15, 2018, CSI
will offer you a severance package equal to what you would have been offered
under such Plan as a Section 16 Officer and the terms of this letter agreement
will be null and void. If your employment is terminated with Cause (as defined
in the Plan) prior to August 15, 2018, you will not be eligible for the
Severance Package set forth herein (or in the Plan). If you resign your
employment with CSI for any reason or die prior to August 15, 2018, you will not
be eligible for the Severance Package set forth herein (or the Plan), unless
otherwise agreed by CSI in writing. For the avoidance of doubt, the parties
agree that as of your signing of this letter agreement, Sections 8.2 and 8.3 of
your Employment Agreement shall be of no further force or effect and shall be
superseded by this letter agreement. In addition, for the avoidance of doubt,
the parties agree that the change of your title from Chief Financial Offer to
Vice President, Administration effective February 7, 2018, and any and all
related changes to your status in connection with such change (including,
without limitation, relative to your authority, duties or responsibilities,
reporting structure or relationships, budget authority, and target bonus), will
not constitute Good Reason under the Plan under any circumstances.

If you agree with the terms outlined in this letter, please sign and date below,
and return to Laura Gillund by February 6, 2018. Larry, we are grateful for your
years of service to CSI and look forward to working with you during the
Transition Period. Please do not hesitate to contact me if you have any
questions.

Sincerely,

/s/ Scott R. Ward
Scott R. Ward
President & Chief Executive Officer

Agreed:

/s/ Laurence L. Betterley                        2/6/18
Laurence L. Betterley                            Date