Methods: Seventy-one consecutive patients (37 males) with congenital MV dysplasia underwent surgery at our institution between January 1996 and March 2006. Patients with atrioventricular canal, atrioventricular discordance or ischemic regurgitation were excluded. Median age at operation was 2.9 years (range 3 days to 20.8 years), twenty-two patients (30%) were less than 12 months old. Associated cardiac lesions were present in 45 patients; seventeen had undergone previous non-mitral cardiac intervention. Mitral incompetence was the predominant lesion in 60 (85%) and stenosis in 11 (15%). Seventy patients underwent primary repair and one patient had primary replacement. Annular dilation and leaflet prolapse was present in 29, cleft MV in 23, papillary to commissural fusion in 8, parachute MV in 4, hammock MV in 2 and other in 5. There were 5 Marfan and 3 Shone syndrome.

Results: In-hospital mortality was 4% (3/71). There was one late non-cardiac death. Median follow-up of 45.3 months (1 to 120) was obtained in 67 survivors. After 60 months, overall survival was 94 ± 2.8%; freedom from re-operation and prosthesis was 76 ± 5.6% and 94 ± 3.6%, respectively. Fourteen patients required 17 mitral re-operations: 14 repairs and 3 replacements. Using univariate analysis, cleft MV was associated with a significantly lower risk of re-operation (p=0.014) while age less than 1 year at surgery (p=0.046), annular dilatation with leaflet prolapse at surgery (p=0.049) and residual valvular dysfunction moderate or greater before hospital discharge (p=0.013) were significant risk factors for re-operation. Multivariate analysis indicated that residual valvular dysfunction (= moderate) prior to discharge was a significant independent risk factor for re-operation (p=0.011). At last follow-up, all patients remain in NYHA class I or II, 6 had moderate valvular dysfunction (5 incompetence, 1 mixed), none had severe.

Conclusion: Repair for congenital mitral valve dysplasia can be performed successfully with low mortality and an acceptable re-operation rate whilst obviating risks associated with valvular prostheses. Suboptimal primary repair was a significant predictor for re-operation but re-repair is most often successful.