This study included 593 HCM patients. Left ventricular MVO was diagnosed when the peak midventricular gradient was estimated as ≥ 30 mm Hg.
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 ± 5.1 years 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 ± 8.0 years after referral to our hospital. By multivariate analysis, maximal wall thickness was an independent determinant of lethal arrhythmic events in MVO-HCM patients.
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.