Comparison of Prevalence, Clinical Course, and Pathological Findings of Left Ventricular Systolic Impairment Versus Normal Systolic Function in Patients With Hypertrophic Cardiomyopathy

Impaired left ventricular systolic function (ILVSF) in hypertrophic cardiomyopathy (HC) is a risk factor for sudden death and a determinant of high mortality. We determined its prevalence, clinical parameters, long-term outcome, and pathologic findings of explanted hearts. We retrospectively analyzed 382 patients with HC; ILVSF was characterized by LV ejection fraction <50% at rest and was identified in 24 patients (6.3%). Patients with ILVSF were younger than patients with normal SF (43.5 ± 14.1 vs 55.3 ± 20.4 years, p = 0.001) and had larger LV end-diastolic cavity diameter (53.2 ± 12.2 vs 43.8 ± 6.2 mm, p = 0.001), larger left atrium (51.2 ± 6.5 vs 44.3 ± 8 mm, p <0.001), and lower fractional shortening (30.7 ± 11.1% vs 45.5% ± 10.3%, p <0.001). A combined end point (heart failure death or heart transplantation) was considered. Median follow-up was 3 years (1.2 to 6.3). Fourteen patients with ILVSF (58.3%) had the end point compared to 3 (0.8%) with normal SF (p <0.001). In explanted hearts, fibrosis represented 30.5 ± 12.5% of the left ventricle; we observed a direct correlation between fibrosis and ventricular dilation (r = 0.794, p = 0.001) and an inverse correlation between fibrosis and ejection fraction (r = −0.623, p = 0.023). Number and length density of small arterioles (<50 μm in diameter) were significantly decreased. In conclusion, ILVSF in HC has a poor prognosis and is associated with fibrosis and selective decreased development of small arterioles.