Sec Form 4 Filing - Blackey Brent G @ Cardiovascular Systems Inc - 2018-08-28

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Blackey Brent G 2. Issuer Name and Ticker or Trading Symbol Cardiovascular Systems Inc [ CSII] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 1225 OLD HIGHWAY 8 NW 3. Date of Earliest Transaction (MM/DD/YY) 08/28/2018 (Street) ST. PAUL, MN55112 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 08/28/2018 A 876 ( 1 ) A $ 0 94,341 D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Restricted Stock Units ( 2 ) ( 2 ) ( 2 ) Common Stock 81,302 81,302 D Restricted Stock Units ( 3 ) 08/15/2019 08/15/2019 Common Stock 2,541 2,541 D Restricted Stock Units ( 3 ) 09/01/2018 09/01/2018 Common Stock 2,855 2,855 D Restricted Stock Units ( 3 ) 09/01/2019 09/01/2019 Common Stock 2,095 2,095 D Restricted Stock Units ( 4 ) 08/28/2018 A 3,527 ( 4 ) ( 4 ) Common Stock 3,527 $ 0 3,527 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Blackey Brent G 1225 OLD HIGHWAY 8 NW ST. PAUL, MN55112 X Signatures /s/ Amanda Lorentz as Attorney-in-Fact for Brent G. Blackey pursuant to Power of Attorney previously filed. 08/30/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents restricted stock received at the election of the reporting person, in lieu of cash payment, as a retainer for service as a director of the Company during fiscal year 2019. ( 2 )Each restricted stock unit represents the right to receive a payment from the Company equal in value to the market price per share of Company common stock on the date of payment and shall be payable in cash or shares of Company common stock beginning six months following the termination of the reporting person's board membership. ( 3 )Each restricted stock unit represents the right to receive a payment from the Company equal in value to the market price per share of Company common stock on the date of payment and shall be payable in cash or shares of Company common stock beginning on the payment date. ( 4 )Each restricted stock unit represents the right to receive a payment from the Company equal in value to the market price per share of Company common stock on the date of payment and shall be payable in cash or shares of Company common stock beginning six months following the termination of each director's board membership; provided, however, that the restricted stock units vest in quarterly amounts of 882 shares on each of September 30, 2018, December 31, 2018 and March 31, 2019 and 881 shares on June 30, 2019.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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