Outcome of septal myectomy for obstructive hypertrophic cardiomyopathy in children and young adults

Background: Obstructive hypertrophic cardiomyopathy (HCM) is an important cause of heart failure in children, but there are limited data addressing outcome of myectomy in children. Our objective was to evaluate the early and late results of septal myectomy in pediatric HCM. Methods: We reviewed 127 consecutive patients (62% male) who underwent transaortic septal myectomy for obstructive HCM from January 1975 to December 2010 at 21 or less years of age. Mean age at operation was 12.9 ± 5.5 years. Preoperatively, mean maximum instantaneous gradient was 89 mm Hg and 95% had significant systolic anterior motion (SAM) with mitral regurgitation (MR). Implantable cardioverter defibrillator (ICD) and permanent pacemaker prior to surgery was present in 21 patients (17%) and 15 (11.7%), respectively. Results: Transaortic extended left ventricular septal myectomy was performed in all patients with no early deaths. Iatrogenic morbidity included new aortic valve regurgitation requiring repair in 7 (5.5%), mitral regurgitation needing repair in 2 (1.5%), ventricular septal defect in 1 (1%), and heart block requiring permanent pacemaker in 1 (1%). An ICD was implanted postoperatively in 8 during the same hospital admission. Mean MIG decreased from 89 to 6 mm Hg (p < 0.0001). Postoperatively, residual chordal SAM was present in 23% with mild or no MR; moderate MR was detected in 1 patient. Four patients (3%) died late during the mean follow-up period of 8.3 years (maximum, 37 years); 1 death was sudden. Overall survival was 98.6%, 94.9%, 92.4%, and 92.4% at 5, 10, 15, and 20 years, respectively. Freedom from any cardiac reoperation was 91.2%, 87.8%, 78.7%, and 72.7% at 5, 10, 15, and 20 years, respectively. Repeat septal myectomy was performed in 6 patients (5%). At late follow-up, 95% were in New York Heart Association functional class I or II and 25 patients underwent late ICD placement. Conclusions: Septal myectomy is safe and effective in children with obstructive HCM, but limited exposure may increase risk of aortic or mitral valve injury. Late survival is better than the previously published untreated natural history of HCM. Patient selection and surgical expertise remain critical components of septal myectomy, especially before considering a prophylactic myectomy in a seemingly asymptomatic patient.