Contrasting clinical properties and exercise responses in obese and lean hypertensive patients

OBJECTIVES We sought to test whether the differences in activity of the ren in-angiotensin and sympathetic nervous systems at rest or during exercise c an explain the differing cardiovascular properties and outcomes of lean and obese hypertensive patients. BACKGROUND Although lean hypertensive patients have fewer metabolic abnorma lities than obese hypertensive patients, paradoxically they appear to have a poorer cardiovascular prognosis. METHODS To evaluate the heightened risks in lean hypertensive patients, thi s study compared metabolic, neuroendocrine and cardiovascular characteristi cs at rest and during a standardized treadmill protocol in obese (body mass index [BMI] = 32.5 +/- 0.3 kg/m(2) n =55) and lean (BMI = 24.3 +/- 0.2 kg/ m(2), n = 66) hypertensive patients. Normotensive obese (n = 21) and lean ( n = 55) volunteers served as control subjects. RESULTS Compared with the lean normotensive subjects, the lean and obese hy pertensive patients had greater left ventricular mass index (LVMI) values, but on multivariate analysis, LVMI correlated with plasma renin activity (p < 0.001) and plasma norepinephrine (PNE) (p < 0.01) in the lean but not th e obese hypertensive patients. Arterial compliance (stroke volume/pulse pre ssure ratio) was reduced in the lean hypertensive patients, in whom it corr elated (p = 0.033) with PNE. The PNE rose less (22%) in the obese than in t he lean (55%) hypertensive patients in response to standing (p < 0.05). Lik ewise, during treadmill exercise, there were lesser increases in renin (65% vs. 145%, p < 0.01) and epinephrine (200% vs. 500%, p < 0.05) in the obese hypertensive patients. These changes were also less in obese patients than in lean control subjects, indicating attenuated neurohormonal responses to stress in obesity. CONCLUSIONS Compared with obese hypertensive patients, cardiovascular prope rties in lean hypertensive patients are more dependent on catecholamines an d the renin system. The different neuroendocrine responses to dynamic stimu li in lean and obese patients also might help to explain the disparity in t heir cardiovascular outcomes. (J Am Cell Cardiol 2001;37:169-74) (C) 2001 b y the American College of Cardiology.