Valve Pathology Influences Repair Outcome and Survival for Congenital Mitral Stenosis
Shuhua Luo1, Lynne E. Nield2, Maruti Haranal1, Juan Contreras1, Kasey Moss1, Steve Fan3, Christopher Caldarone1, Glen S. Van Arsdell1, Osami Honjo1.
1Cardiovascualr surgery Hospital for Sick Children, Toronto, ON, Canada, 2Cardiology Hospital for Sick Children, Toronto, ON, Canada, 3Hospital for Sick Children, Toronto, ON, Canada.
Objective: we hypothesized that pathology and mechanism of congenital mitral stenosis(CMS) influences the outcome of mitral valve(MV) repair and survival.
Methods: Fifty-five consecutive CMS patients(2012-2017) who underwent MV repair were included. Original echocardiographic images were reviewed to delineate valve pathology. Kaplan-Meier analysis and Cox regression were used for survival and predictors analyses.
Results: The median age and body weight at operation were 4.3(1.0-17.9) years and 20(7.7-62.0)kg respectively. Twenty-eight(50.9%) patients associated with left ventricle outflow tract obstruction(LVOTO); 10(18.2%) had>moderate mitral regurgitation(MR). The dominant etiology was typical MS(n=18), supravalvar ring(n=17), parachute valve(n=12), and Hammock valve(n=8). The median inflow pressure gradient across MV was significantly improved from 19.0(14.5-30.0) mmHg to 7(5.6-18)(p<0.001) after repair, and remained unchanged at last follow-up(p=0.57). The most common repair techniques were ring resection(n=29) and papillary muscle splitting(n=26), followed by chordal fenestration(n=16) and commissurotomy(n=17). Two patients required replacement in the same operation. The overall freedom from mortality/transplant was 91% at 1 year, 86% at 3 years and 82% at 5 years. Five patients required reintervention. The majority(39/40) of patients had Ross score≤1 at the 3-year follow-up. Multivariable analysis and Kaplan-Meier curve(Figure) revealed that hammock valve(p=0.028) and LVOTO(p=0.006) as the risk factors for mortality/transplant.
Conclusion: MV repair is an effective and durable treatment for CMS with reasonable medium-term functional outcome. Certain anatomic features, Hammock valve or the presence of LVOTO, are associated with poor outcome. 
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