Surgical septal myectomy decreases the risk for appropriate implantable cardioverter defibrillator discharge in obstructive hypertrophic cardiomyopathy

Abstract

Aims: To determine the impact of surgical myectomy on ventricular arrhythmias in obstructive hypertrophic cardiomyopathy (HCM). Left ventricular outflow tract obstruction (LVOTO) correlates with adverse outcomes, including sudden cardiac death (SCD) in patients with HCM. Surgical myectomy is the primary treatment strategy for relief of symptoms owing to LVOTO and has been hypothesized to decrease the potential for ventricular tachyarrhythmias.

Methods and results: We reviewed the Mayo Clinic HCM database for those patients with HCM who had received implantable cardioverter defibrillator (ICD) and grouped the patients into myectomy and non-myectomy groups. Retrospective analysis of the incidence of SCD and appropriate ICD discharge was performed in addition to the analysis of ICD interrogation records. A total of 125 patients defined by these parameters were followed at the Mayo Clinic between 1992 and 2005. New York Heart Association functional class, anti-arrhythmic drug usage, wall thickness, and reasons for ICD implantation were similar between the groups; 118 patients underwent ICD implantation for primary prevention and seven for secondary prevention after sustained ventricular arrhythmias. There were no SCDs during this follow-up period in either group, whereas 12 (17%) patients in the non-myectomy group and only one (2%) patient in the myectomy group sustained appropriate ICD discharges. The average annualized event rate was 4.3% per year in the non-myectomy group, compared with 0.24% per year following myectomy (P = 0.004).

Conclusion: These data suggest that surgical myectomy, primarily performed to relieve outflow tract obstruction and severe symptoms in HCM, is associated with a marked reduction in the incidence of appropriate ICD discharge and risk for SCD.