<PAGE>


                                   UNITED STATES
                         SECURITIES AND EXCHANGE COMMISSION

                              WASHINGTON, D.C.  20549

                                  FORM 10-Q/A (No.1)


/X/ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15 (d) OF THE SECURITIES 
    EXCHANGE ACT OF 1934 FOR THE QUARTERLY PERIOD ENDED MARCH 31, 1998

/ / TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 (d) OF THE SECURITIES 
    EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM ______________ 
    TO ______________.


COMMISSION FILE NO. 0-22233


ENDOCARDIAL SOLUTIONS, INC.
---------------------------
(EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)


DELAWARE                                          41-1724963
--------                                          ----------
(STATE OR OTHER JURISDICTION OF                   (IRS EMPLOYER
INCORPORATION OR ORGANIZATION)                    IDENTIFICATION NUMBER)


1350 ENERGY LANE                                  (612) 644-7890
SUITE 110                                         --------------
SAINT PAUL, MINNESOTA  55108                      (REGISTRANT'S TELEPHONE NUMBER
----------------------------                      INCLUDING AREA CODE)
(ADDRESS OF PRINCIPAL EXECUTIVE OFFICES
AND ZIP CODE)


INDICATE BY CHECK MARK WHETHER THE REGISTRANT (1) HAS FILED ALL REPORTS 
REQUIRED TO BE FILED BY SECTION 13 OR 15 (d) OF THE SECURITIES EXCHANGE ACT 
OF 1934 DURING THE PRECEDING TWELVE (12) MONTHS (OR FOR SUCH SHORTER PERIOD 
THAT THE REGISTRANT WAS REQUIRED TO FILE SUCH REPORTS) AND (2) HAS BEEN 
SUBJECT TO SUCH FILING REQUIREMENTS FOR THE PAST 90 DAYS.

          YES  X       NO
             ------      ------

INDICATE THE NUMBER OF SHARES OUTSTANDING OF EACH OF THE ISSUER'S CLASSES OF 
COMMON STOCK, AS OF THE LATEST PRACTICABLE DATE.

COMMON STOCK, $.01 PAR VALUE                        8,976,182
----------------------------    
(Class)                         (NUMBER OF SHARES OUTSTANDING AT MARCH 31, 1998)




<PAGE>

The undersigned registrant hereby amends Part II, Item 6(a), entitled 
"Exhibits", of its Quarterly Report on Form 10-Q for the quarter ended March 
31, 1998 to amend and refile Exhibit 10.1.

PART II.  OTHER INFORMATION

ITEM 6.   EXHIBITS AND REPORTS ON FORM 8-K

(a)  Exhibits

<TABLE>
<CAPTION>
Exhibit        Description
-------        -----------
<S>           <C>
10.1**         License Agreement, dated January 30, 1998, between the Company
               and Medtronic, Inc.

27*            Financial Data Schedule (EDGAR filing only)

99*            Cautionary Statement
</TABLE>

*   Previously filed.

**  Pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as 
amended, confidential portions of Exhibit 10.1 have been deleted and filed 
separately with the Securities and Exchange Commission pursuant to a request 
for confidential treatment.

(b)  Reports

The Company filed no reports on Form 8-K during the quarter ended March 31, 
1998.


<PAGE>

                                 SIGNATURES


Pursuant to the requirements of the Securities Exchange Act of 1934, the 
registrant has duly caused this report to be signed on its behalf by the 
undersigned thereunto duly authorized.

                                       ENDOCARDIAL SOLUTIONS, INC.



Dated: July 31, 1998                  By: /s/ James W. Bullock
                                          -------------------------------------
                                          James W. Bullock
                                          President and Chief Executive Officer
                                          (Principal Executive Officer)


Dated: July 31, 1998                  By: /s/ Leota L. Pearson
                                          -------------------------------------
                                          Leota L. Pearson
                                          Controller
                                          (Principal Financial and Accounting 
                                          Officer)