The Framingham Heart Study

Previous reports indicate that cardiac output is increased early in the course of hypertension. The purpose of this study was to identify with echocardiography hemodynamic features in normotensive adults that predicted the development of hypertension. Framingham Heart Study subjects were eligible for this investigation if they were normotensive at the baseline examination (systolic blood pressure <140 mm Hg, diastolic blood pressure <90 mm Hg, and no antihypertensive medications) and if they were free of coronary heart disease, congestive heart failure, valvular heart disease, atrial fibrillation, hypertrophic cardiomyopathy, diabetes mellitus, and renal insufficiency. The study included 1118 men (mean age, 44 years) and 1559 women (mean age, 46 years). After 4 years of follow-up, of this normotensive cohort, 201 men (18.0%) and 257 women (16.5%) had developed hypertension. In separate, age-adjusted multivariable logistic regression analyses, increased cardiac index (men: odds ratio=1.19 for one standard deviation increment, P=.O3; women: odds ratio=1.17, P=.O2) and end-systolic wall stress (men: odds ratio=1.24, /=.006; women: odds ratio=1.43, P<.001) were related to the development of hypertension in both sexes. In addition, increased heart rate in men (odds ratio=1.25, Increased left ventricular mass has been shown to be a predictor of changes in blood pressureand the development of hypertension.An increase in left ventricular mass may contribute to the pathogenesis of hypertension by promoting a hyperdynamic state. It is unknown whether hemodynamic alterations are present in the preclinical stage of hypertension that may lead to the development of hypertension. Several small prospective studies have shown that early in the course of hypertension there is a hyperkinetic circulation, during which peripheral resistance is normal and cardiac index is increased. As hypertension progresses, peripheral resistance gradually increases and cardiac index falls. The hemodynamic characteristics of the preclinical stage of hypertension have not been investigated. The purpose of this study was to assess the hemodynamic predictors of incident hypertension by use of Received September 30,1993; accepted in revised form June 15, 1994. From the Framingham Heart Study, Framingham, Mass (W.S.P., M.G.L., D.L.); the divisions of Cardiology and Clinical Epidemiology (D.L.), Beth Israel Hospital, Boston, Mass; The National Heart, Lung, and Blood Institute, Bethesda, Md (D.L.); and the divisions of Epidemiology and Preventive Medicine, Boston University, School of Medicine, Boston, Mass (W.S.P., M.G.L., D.L.). Reprint requests to Daniel Levy, MD, Framingham Heart Study, 5 Thurber St, Framingham, MA 01701. © 1994 American Heart Association, Inc. P=.OO6) was a significant predictor of hypertension. After adjustment for age and baseline blood pressure, none of the hemodynamic variables was a significant predictor of hypertension. In addition, load-independent indexes of contractility revealed only a minimally greater proportion of subjects with increased contractility at baseline in the group that developed hypertension compared with those who remained normotensive. The present study revealed a hemodynamic profile in the preclinical stage of hypertension in age-adjusted analyses that was similar to the hyperkinetic circulatory phase found in the early stage of hypertension in some previous studies; however, after controlling for age and baseline blood pressure, none of the hemodynamic parameters were significant predictors of the development of hypertension. Knowledge of an individual's hemodynamic profile does not improve the prediction of hypertension risk that can be obtained from baseline blood pressure and age alone. Further studies are warranted to investigate hemodynamic features in various stages of hypertension after adjustment for age and blood pressure. (Hypertension. 1994;24:585-590.)