Implantable cardioverter defibrillator therapy and sudden death risk stratification in hypertrophic cardiomyopathy patients with midventricular obstruction: A single-center experience.

BACKGROUND: Previous studies reported that the presence of midventricular obstruction (MVO) was an independent determinant of sudden death and potentially lethal arrhythmic events in patients with hypertrophic cardiomyopathy (HCM). However, it remains unclear whether implantable cardioverter defibrillator (ICD) improves survival in HCM patients with MVO. In addition, the risk factors for lethal arrhythmic events in MVO-HCM patients are not fully understood. The aim of this study was to provide an overview of the ICD therapy on sudden death prevention, and to determine the risk factors for lethal arrhythmic events in MVO-HCM patients.

METHODS: This study included 593 HCM patients. Left ventricular MVO was diagnosed when the peak midventricular gradient was estimated as ≥30mmHg.

RESULTS: MVO was identified in 56 patients (9.4%), and 15 of the 56 MVO-HCM patients (26.8%) received an ICD. Six of 15 ICD-implanted patients (40.0%) had appropriate ICD interventions over the follow-up period of 6.5±5.1years after ICD implantation. Although two of 42 patients without an ICD died suddenly, no patients experienced sudden death after ICD implantation in patients with an ICD throughout the follow-up period of 9.0±8.0years after referral to our hospital. By multivariate analysis, maximal wall thickness was an independent determinant of lethal arrhythmic events in MVO-HCM patients.

CONCLUSIONS: A quarter of MVO-HCM patients received an ICD, and the incidence of appropriate ICD intervention was about 6.2%/year. It may be necessary to give careful consideration to the prevention of lethal arrhythmic events in MVO-HCM patients, especially those with severe left ventricular hypertrophy.