Comparison of the prevalence, clinical features, and long-term outcomes of midventricular hypertrophy vs apical phenotype in patients with hypertrophic cardiomyopathy.

Previous studies on the association between the distribution of left ventricle hypertrophy and the clinical features of hypertrophic cardiomyopathy (HCM) have yielded unclear results. The aim of this study was to investigate the differences in the prevalence, clinical features, management strategies, and long-term outcomes between patients with midventricular hypertrophic obstructive cardiomyopathy (MVHOCM) and patients with apical HCM (ApHCM).A retrospective study of 60 patients with MVHOCM and 263 patients with ApHCM identified in a consecutive single-centre cohort consisting of 2068 patients with HCM was performed. The prevalence, clinical features, and natural history of the patients in these 2 groups were compared.Compared with ApHCM patients, patients with MVHOCM tended to be much younger and more symptomatic during their initial evaluation. Over a mean follow-up of 7 years, the probability of cardiovascular mortality and that of morbidity was significantly greater in MVHOCM patients compared with ApHCM patients (log-rank, P < 0.001).Our results suggest that, compared with ApHCM, MVHOCM represents an uncommon presentation of the clinical spectrum of HCM that is characterized by progressive clinical deterioration leading to increased cardiovascular mortality and morbidity. Our results also underscore the importance of the timely recognition of MVHOCM for the prediction of prognosis and the early consideration of appropriate management strategies.