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

BACKGROUND Repair is preferable for children with mitral valve disease; mitral valve replacement (MVR) is occasionally necessary. We present the results of a multi-institutional Investigational Device Exemption trial of the 15mm St. Jude mechanical mitral valve. METHODS From May, 2015, to March, 2017, 23 children aged 0.4-27.4 months (mean 7.8 months; 85% <1 year) weighing 2.9-10.9 kg (mean 5.5 kg) at 15 centers underwent MVR with a 15mm SJM (intra-annular 45%, supra-annular 55%). 21 (91%) had prior cardiac operations. Follow-up until death, valve explantation, or five years postoperatively was 100% complete. RESULTS There were 6 mortalities all in the first 12 months; no death was valve related. Four patients required a pacemaker (2 supra-annular, 2 intra-annular). Three patients had thrombosis requiring valve explantation at 13, 21 and 35 days postoperatively. Two of these 3 patients were on low molecular weight heparin for anticoagulation, 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%). One and five-year freedom from death or valve explantation was 71.0%. CONCLUSIONS In small children with severe mitral valve disease requiring MVR, the 15mm SJM MHV 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.