Clinical Long-Term Outcome Is Favorable in Patients with Hypertrophic Obstructive Cardiomyopathy Undergoing Septal Myectomy during Childhood

Objectives: To describe the long-term clinical outcome of patients with hypertrophic cardiomyopathy (HCM) and severe left ventricular outflow tract (LVOT) obstruction undergoing surgical transaortic septal myectomy during childhood. Methods: Clinical, echocardiographic, electrocardiographic, Holter, stress test and genetic data were extracted by retrospective chart review; 8 patients underwent prospective detailed clinical evaluation including cardiac magnetic resonance imaging (CMR) with contrast. Results: From 1978 to 2014, septal myectomy was performed in 21 patients (12 males) at a median age of 1.08 [0.18–18] years. The genetic diagnosis was Noonan syndrome in nine, familial nonsyndromic HCM in five, LEOPARD syndrome in two,and unknown in fivepatients. Hospital stay was in median 27 (13–108) days. Homologous blood transfusion was given intraoperatively in 10 patients. Perioperatively, one patient with LEOPARD syndrome died. Complications, such as arrhythmias, pleural and pericardial effusions, infection, or intracerebral embolus, occurred in 5 patients. New mitral valve regurgitation occurred in 1 patient, new aortic valve regurgitation in 2 patients, and new complete bundle branch block in 6 patients. No patient developed an atrioventricular block. There was a lasting reduction of the LVOT gradient, systolic anterior motion of the mitral valve, and the thickness of the intraventricular septum, as well as a lasting improvement of the clinical status (expressed as NYHA/Ross) in the 5-year and long-term postoperative follow-up (median 17 [7–27] years). No patient required re-operation. On CMR T1 mapping, there was no difference between interstitial fibrosis around the surgical area as compared with the remaining myocardium. Conclusion: Septal myectomy performed during childhood causes lasting LVOT gradient reduction and improvement of clinical status in pediatric patients with obstructive HCM.