Background: Anterior mitral leaflet cleft, which is one of the most important causes for congenital mitral regurgitation, is usually associated with interatrial septal defects.

Methods: Fifty-three patients with anterior mitral leaflet cleft associated with interatrial septal defects were operated between 1985 and April 2001. There were 30 (56.6%) women and 23 (43.4%) men with a mean age 21.6 ± 12.2 years (range 2 to 55 years). Atrial septal defect was primum type in 49 (92.4%) patients and secundum type in 4 (7.6%) patients. There were two cleft on the right atrioventricular valve. Fifty-one patients had sinus rhythm. Functional capacity decreased in 10 patients (NYHA class III). The mean mitral regurgitation was 2.3 ± 0.7 degree (range 1 to 4). Pericardial or prosthetic patch was used to close atrial septal defects. All clefts were closed with interrupted suture technique. Coronary sinus was left on the left side in three patients. Total follow-up was 348 patient-years, with a mean of 6.5 ± 3.8 years (range, 0.2 to 15 years).

Results: There was no early or late mortality. Transient atrioventricular block developed in three (5.7%) patients in the early postoperative period and only one (1.9%) patient required replacement of a permanent pacemaker. Fifty-one patients had mild or no mitral regurgitation after operation. Two (3.8%) patients underwent reoperation, and one patient received mitral valve replacement, and re-closure of residual cleft with residual atrial septal defect through pericardial patch was performed in the other. Actuarial freedom form reoperation was 91.7% ± 5.8% at 14.5 years.

Conclusions: Treatment of congenital anterior mitral leaflet cleft associated with interatrial septal defect is surgical. Patients, who are diagnosed late, can be operated successfully before congestive heart failure develops. The most important late complication is necessity of a reoperation. The most significant factor effecting long-term outcome is the successfull repair of anterior mitral leaflet cleft.