Clinical characteristics and prognosis of 60 patients with midventricular obstructive hypertrophic cardiomyopathy.

Background: Midventricular obstructive hypertrophic cardiomyopathy (MVOHCM) is a rare form of hypertrophic cardiomyopathy. Knowledge regarding the diagnosis, morbidity and cardiovascular mortality is limited. In this study, we aimed to describe the long-term outcomes of patients with MVOHCM followed in a tertiary referral centre.Methods A retrospective study of 60 patients with MVOHCM diagnosed at FuWai Hospital was performed. Clinical features, mortality and cardiovascular morbidity were analysed.

Results: The 60 patients with MVOHCM represented 2.9% of all the hypertrophic cardiomyopathy cases (n = 2068). At diagnosis, the mean age was 40.2 ± 15.0 years. During 7.1 ± 6.3 years of follow-up after diagnosis, the cardiovascular mortality was 15.0%. The probability of survival at 10 years was 77.0 ± 8.0%. The following two predictors of cardiovascular mortality were identified: severe ventricular septal hypertrophy at least 30  mm (hazard ratio, 3.19; P = 0.031) and unexplained syncope (hazard ratio, 4.59; P = 0.002) at baseline. Thirty patients (50.0%) had one or more morbid events, and the most frequent was nonsustained ventricular tachycardia. Apical aneurysm formation was identified in 20% of patients, and the patients with apical aneurysms were more inclined to experience nonsustained ventricular tachycardia than patients without apical aneurysm (58.3 vs. 16.7%; P = 0.003). Peak pressure gradient at least 70  mm Hg (hazard ratio, 3.00; P = 0.01) at baseline was identified as the only predictor of apical aneurysm.

Conclusion: In Chinese patients, MVOHCM is associated with an unfavourable prognosis of cardiovascular mortality. One-half of these patients experience major cardiovascular events, and 20% develop an apical aneurysm, which significantly increases arrhythmia events. These data warrant measures to ensure the early recognition of MVOHCM followed by appropriate therapeutic interventions.