Influence of left ventricular cavity size on clinical presentation in hypertrophic cardiomyopathy

The aim of this study was to assess whether left ventricular (LV) cavity si ze relates to functional impairment and syncope in patients with hypertroph ic cardiomyopathy (HC). LV diastolic dysfunction influences functional limi tation in HC. A reduced LV end-diastolic dimension may underlie impaired di astolic properties and be implicated in hemodynamic syncope. Eighty-two con secutive patients with HC (off drugs, in sinus rhythm) underwent echocardio graphy to measure LV end-diastolic dimension in the short-axis view (indexe d to the body surface area) and radionuclide angiography (n = 50) to calcul ate peak filling rate (normalized to stroke counts/s). Patients in New York Heart Association functional classes II to IV had smaller LV end-diastolic dimension (23.2 +/- 2.6 vs 25.5 +/- 2.5 mm/M-2, p = 0.0001) and lower peak filling rate (4.3 +/- 1.4 vs 5.1 +/- 1.3 stroke counts/s, p = 0.036) than those in New York Heart Association class I. LV end-diastolic diameter was correlated to peak filling rate (r = 0.37; p = 0.008). The most potent pred ictors of functional limitation were LV end-diastolic dimension (relative r isk [RR] 0.63, confidence interval [CI] 0.45 to 0.88; p = 0.008), age (RR 1 .09, CI 1.03 to 1.17; p = 0.003), and LV thickness score (RR 1.08, CI 1.02 to 1.13; p = 0.003). LV cavity size was smaller in patients with functional limitation irrespective of obstruction and hypertrophy. Patients with diff ered from those without a history of syncope for a smaller LV end-diastolic dimension (23.2 +/- 2.5 vs 25.0 +/- 2.7 mm/M-2, p = 0.008), which was the only independent predictor of syncope (RR 0.77, CI 0.63 to 0.95; p = 0.013) . Thus, a small LV cavity size is associated with functional limitation and history of syncope in HC. (C) 1999 by Excerpta Medica, Inc.