Prognosis of apical hypertrophic cardiomyopathy in patients with an implantable cardioverter defibrillator

Abstract Background Prophylactic use of implantable cardioverter-defibrillators (ICDs) to prevent sudden cardiac death (SCD) is widely spread all over the world in patients with hypertrophic cardiomyopathy (HCM). Apical HCM is a phenotype variant of HCM, with hypertrophy predominantly affecting apex, that was initially described 30 years ago. Apical HCM patients may have different clinical prognosis compared with other subsets of HCM. In previous studies, apical HCM patients seem to have a more benign prognosis than other types of HCM. However, little is known about the long-term outcomes of apical HCM and there are many unclear points. Moreover, there are few reports about the clinical prognosis in apical HCM patients with an ICD. Objective The aim of this study is to identify the difference between the prognosis of apical and the other HCM patients with an ICD. Methods We retrospectively analyzed the database of our ICD clinic. All subjects had been implanted with an ICD from October 2006 to August 2017. We classified HCM patients into LV outflow tract obstruction (LVOTO) and midventricular obstruction (MVO), apical HCM and other non-obstructive types. We divided all the patients into apical and other types of HCM, and examined their background, incidence of appropriate ICD therapies, hospitalization for heart failure, electrical storm and death. Results A total of consecutive 62 Japanese HCM patients with an ICD (follow-up period, 86±25 months; age, 67±14 years; male sex, 85%; left ventricular ejection fraction, 57±12%; LV max wall-thickness, 19±5mm; LV apical aneurysm, 9.7%; HCM Risk-SCD, 4.4±3.0) were enrolled in this study. We classified them into 14 apical HCM and 48 other types of HCM patients. The clinical characteristics and major events of these patients are shown in the Figure. During the follow-up periods, there were no significant differences in the incidence of hospitalization for heart failure, electrical storm and death between the 2 groups (p=0.40; p=0.22; p=0.23). Appropriate therapies occurred in 5 of 14 (36%) patients with apical HCM and 4 of 48 (8.3%) patients with other types of HCM (p=0.022). Conclusions Appropriate ICD therapy was more prevalent in patients with apical HCM, compared to patients with other types of HCM. However, the incidences of hospitalization for heart failure, electrical storm and death were not significantly different between two groups. Funding Acknowledgement Type of funding sources: None.