Statement of Changes in Beneficial Ownership (4)

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 OF SECURITIES	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response... 0.5
	Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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/YYYY) 9/1/2018
(Street) ST. PAUL, MN 55112 (City)        (State)        (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	6. Individual or Joint/Group Filing (Check Applicable Line) _ X _ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. 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	9/1/2018		M		2855	A	$0   (1)	97196	D

Table II - Derivative Securities Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. 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		7. Title and Amount of Securities Underlying Derivative Security (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	81302		81302	D
Restricted Stock Units	(3)							8/15/2019	8/15/2019	Common Stock	2541		2541	D
Restricted Stock Units	(3)	9/1/2018		M			2855	9/1/2018	9/1/2018	Common Stock	2855	$0	0	D
Restricted Stock Units	(3)							9/1/2019	9/1/2019	Common Stock	2095		2095	D
Restricted Stock Units	(4)							(4)	(4)	Common Stock	3527		3527	D

Explanation of Responses:
(1)	Restricted stock units were paid in shares of common stock on a one-for-one basis.
(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.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Blackey Brent G 1225 OLD HIGHWAY 8 NW ST. PAUL, MN 55112	X

Signatures
/s/ Amanda Lorentz as Attorney-in-Fact for Brent G. Blackey pursuant to Power of Attorney previously filed.		9/5/2018
** Signature of Reporting Person		Date

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).
Note:	File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.