Mitral valve replacement in infants and children 5 years of age or younger: evolution in practice and outcome over three decades with a focus on supra-annular prosthesis implantation.

OBJECTIVE: Successful mitral valve replacement in young children is limited by the lack of small prosthetic valves. Supra-annular prosthesis implantation can facilitate mitral valve replacement with a larger prosthesis in children with a small annulus, but little is known about its effect on the outcomes of mitral valve replacement in young children.

METHODS: One hundred eighteen children underwent mitral valve replacement at 5 years of age or younger from 1976-2006. Mitral valve replacement was supra-annular in 37 (32%) patients.

RESULTS: Survival was 74% +/- 4% at 1 year and 56% +/- 5% at 10 years but improved over time (10-year survival of 83% +/- 7% from 1994-2006). Factors associated with worse survival included earlier mitral valve replacement date, age less than 1 year, complete atrioventricular canal, and additional procedures at mitral valve replacement, but not supra-annular mitral valve replacement. As survival improved during our more recent experience, the risks of supra-annular mitral valve replacement became apparent; survival was worse among patients with a supra-annular prosthesis after 1991. A pacemaker was placed in 18 (15%) patients within 1 month of mitral valve replacement and was less likely in patients who had undergone supra-annular mitral valve replacement. Among early survivors, freedom from redo mitral valve replacement was 72% +/- 5% at 5 years and 45% +/- 7% at 10 years. Twenty-one patients with a supra-annular prosthesis underwent redo mitral valve replacement. The second prosthesis was annular in 15 of these patients and upsized in all but 1, but 5 required pacemaker placement for heart block.

CONCLUSIONS: Supra-annular mitral valve replacement was associated with worse survival than annular mitral valve replacement in our recent experience. Patients with supra-annular mitral valve replacement were less likely to have operative complete heart block but remained at risk when the prosthesis was subsequently replaced.