Usefulness of mitral regurgitation as a marker of increased risk for death or cardiac transplantation in idiopathic dilated cardiomyopathy in children

In adults with idiopathic dilated cardiomyopathy (IDC), mitral regurgitation (MR) is associated with adverse prognosis and is often addressed by surgery or intervention. MR is commonly found in children with IDC, but its prognostic relevance has not been defined, and interventions to reduce MR are not routinely performed in this population. In this study, it was hypothesized that MR is an independent risk factor for death or transplantation. This was a single-center, retrospective study of sequential patients with IDC or familial IDC (left ventricular end-diastolic dimension z score >2 and ejection fraction <50%). Patients with acute myocarditis or previous mitral surgery were excluded. MR severity was graded according to American Society of Echocardiography guidelines as mild, moderate, or severe on the basis of MR jet vena contracta width. Left ventricular end-diastolic volume, end-systolic volume, and ejection fraction were measured by biplane Simpson's method. Forty-two children with IDC were studied. The mean follow-up period was 25 months. At initial assessment, 34 children (82%) were taking angiotensin-converting enzyme inhibitors, 25 (60%) furosemide, 27 (65%) β blockers, and 7 (17%) intravenous inotropes. The mean indexed end-systolic volume was 91 ± 51 ml/m². The mean ejection fraction was 27 ± 16%. MR was mild in 42%, moderate in 19%, severe in 2%, and absent in 35% of patients. MR severity progressed from initial to last evaluation. MR severity was an independent risk factor for lower freedom from death or transplantation. Progression in MR severity increased the annual hazard of death or transplantation by a factor of 2.4 (p = 0.003). In conclusion, MR severity is independently associated with worse clinical status and decreased freedom from death or transplantation in children with IDC.