Maximal Aerobic Capacity Determinants in Hypertensive Heart Disease with Normal Ejection Fraction

Abstract

To analyze the determinants of impaired exercise tolerance in hypertensive patients, a study was made of 45 patients (42% males, mean age 65 ± 4 years) with systemic arterial hypertension, left ventricular hypertrophy (ventricular mass ≥100 g/m^2), in sinus rhythm and having no prior history of ischemic heart disease. Twenty had been hospitalized within the past 4 weeks for congestive heart failure (dyspnea and chest x-ray verified pulmonary edema), while 25 were asymptomatic. Following remission of symptoms after 2-5 days' treatment with diuretics, and withdrawal of antihypertensive drugs, testing revealed impaired exercise tolerance (V(O2max)) (17 ± 3.1 vs. 23.5 ± 3.8 cm^3/kg/min, p < 0.001) and a lower peak ventricular filling rate (2.4 ± 0.4 vs. 3.6 ± 0.6 end-diastolic counts per second) evaluated using technetium- 99 (gated equilibrium method). Ejection fraction and peak ejection rates were normal in both groups. Regional ischemia was ruled out (thallium-201-negative in ergometrie tests) in 32 patients, 12 of whom had impaired (V(O2max)) (<20 cm^3/kg/min) while 20 were normal (>20 cm^3/kg/min). The group of 12 had a higher left ventricular mass per body surface (131 ± 21 vs. 119 ± 12 g/ m^2, p < 0.01). In a group of 26 patients having similar degrees of hypertrophy, of which 9 were thallium-positive and 17 thallium-negative at peak stress, was significantly lower in the first (18.4 ± 3.9 vs. 23.5 ± 4.8 cm^3/kg/min, p < 0.01). In conclusion, in hypertensive patients with left ventricular hypertrophy and normal ejection fraction, exercise tolerance depends on prior congestive heart failure, degree of left ventricular hypertrophy and the presence of regional myocardial ischemia.