Relation of various degrees of body mass index in patients with systemic hypertension to left ventricular mass, cardiac output, and peripheral resistance (The Hypertension Genetic Epidemiology Network Study)

The impact of different methods of indexation of left ventricular (IV) mass and systemic hemodynamic variables on prevalences and correlates of cardio vascular abnormalities in relation to level of obesity in populations remai ns unclear. We evaluated 1,672 participants in the Hypertension Genetic Epi demiology Network Study to investigate the relations of overweight and leve l of obesity to LV mass and prevalences of LV hypertrophy, abnormal cardiac output, and peripheral resistance detected using different indexations for body size. In our study population, 1,577 subjects were clinically healthy nondiabetic hypertensive and 95 were normotensive normal-weight nondiabeti c reference subjects. Fat-free mass (FFM) did not differ between the refere nce group and the normal-weight hypertensive subjects, and increased with o verweight. In hypertensive subjects, IV mass and cardiac output increased a nd total peripheral resistance decreased with overweight. indexation of IV mass for FFM or body surface area (BSA) resulted in no difference or even l ower prevalence of IV hypertrophy in severely obese compared with normal-we ight hypertensive subjects. in contrast, indexation of LV mass for height(2 .7) identified an increased prevalence of IV hypertrophy with overweight an d obesity. Absolute cardiac output increased and total peripheral resistanc e decreased with overweight. Prevalence of elevated cardiac output indexed for height(1.83) increased and for elevated total peripheral resistance-hei ght(1.83) index decreased with greater overweight, whereas opposite trends were seen when cardiac output and total peripheral resistance were indexed for BSA or FFM. Thus, in hypertensive subjects, FFM increases with overweig ht and is directly related to LV mass, stroke volume, and cardiac output, a nd inversely related to total peripheral resistance. Indexations of LV mass and systemic hemodynamics for FFM or BSA obscured associations of LV hyper trophy and abnormal cardiac and total peripheral resistance indexes with ov erweight, whereas LV mass/height(2,7), cardiac output/height(1.83), and tot al peripheral resistance-height(1.83) detected significant preclinical card iovascular abnormalities with obesity. (C) 2001 by Excerpta Medica, Inc.