Importance of obesity, race and age to the cardiac structural and functional effects of hypertension

Abstract

Objectives. The purpose of this study was to determine the effects of obesity and its interaction with age, race and the magnitude of blood pressure elevation in a large cohort of patients with mild to moderate hypertension and a high prevalence of left ventricular hypertrophy.Background. Obesity, race and age each have important effects on the incidence and severity of hypertension and may contribute to the effects of blood pressure elevation on the cardiac manifestations of hypertension.Methods. Left ventricular structure and function were assessed with two-dimensional targeted M-mode echocardiography in 692 men with mild to moderate hypertension (average blood pressure 153/100 mm Hg), and the data were compared in relation to obesity (determined from body mass index), age, race, blood pressure, physical activity, plasma renin activity, urinary sodium excretion, hematocrit, heart rate and serum lipids.Results. Left ventricular hypertrophy was common (630% with increased left ventricular mass, 22% with left ventricular hypertrophy on the electrocardiogram [ECG]). On multivariable regression analysis, body mass index was the strongest predictor of left ventricular mass and magnified the slope relation of blood pressure to left ventricular mass. Despite a greater prevalence of ECG left ventricular hypertrophy in blacks (31%) than in whites (10%), left ventricular mass and echocardiographic prevalence of left ventricular hypertrophy did not differ by race. However, septal, posterior left ventricular and relative wall thickness were greater in black than in white men.Conclusions. Obesity is the strongest clinical predictor of left ventricular mass and left ventricular hypertrophy la men, even in those with mild to moderate hypertension of sufficient severity to be associated with a high prevalence of left ventricular hypertrophy. Moreover, independent effects of systolic blood pressure on left ventricular mass an amplified by obesity. Although race does not affect left ventricular mass or the prevalence of left ventricular hypertrophy, black race is associated with greater relative wall thickness, itself a predictor of unfavorable cardiovascular outcome.