Mitral Valve Replacement in Infants and Children: Five-Year Outcomes of the HALO Clinical Trial.

ABSTRACT

BACKGROUND: Repair is preferable for children with mitral valve disease, but mitral valve replacement (MVR) is occasionally necessary. This report presents the results of a multiinstitutional Investigational Device Exemption trial of the 15-mm St Jude (SJM) mechanical mitral valve (Abbott Structural Heart). METHODS: From May 2015 to March 2017, 23 children aged 0.4 to 27.4 months (mean, 7.8 months; 85% <1 year) weighing 2.9 to 10.9 kg (mean, 5.5 kg) at 15 centers underwent MVR with a 15-mm SJM mechanical mitral valve (intraannular, 45%; supraannular, 55%). A total of 21 (91%) of the children had undergone previous cardiac operations. Follow-up until death, valve explantation, or 5 years postoperatively was 100% complete. RESULTS: There were 6 deaths, all in the first 12 months; no death was valve related. Four patients required a pacemaker (2 supraannular, 2 intraannular). Three patients had thrombosis requiring valve explantation at 13, 21, and 35 days postoperatively. Two of these 3 patients were receiving low-molecular-weight heparin for anticoagulation, and the third had factor V Leiden deficiency. There were 5 nonfatal bleeding complications within 4 months of MVR (1-year freedom from bleeding, 71.0%). The 1- and 5-year freedom from death or valve explantation was 71.0%. CONCLUSIONS: In small children with severe mitral valve disease requiring MVR, the 15-mm SJM mechanical mitral valve provides satisfactory hemodynamics. Mortality and complications in these patients are not trivial. Low-molecular-weight heparin likely should be avoided as primary anticoagulation. Eventual valve replacement is inevitable.