Heterogeneity of Cardiorenal Characteristics in Normotensive Subjects

Abstract

Blood pressure is a marker of elevated risk for cardiovascular disease, even within the normotensive range. The present study evaluates cardiorenal modifications observed in normotensive (<140/90 mm Hg) subjects. Using World Health Organization–International Society of Hypertension definitions, 265 normotensive subjects were categorized as having optimal (n=73), normal (n=84), and high-normal (n=108) blood pressure. Renal hemodynamics and function and cardiac morphology were evaluated by isotopic clearance techniques and ultrasonography, respectively. Urinary albumin excretion was measured in 24-hour urine collections. Body mass index and 24-hour urinary sodium (estimate of sodium intake), as well as left ventricular mass index, relative wall thickness, and glomerular filtration rate and filtration fraction, progressively increased in the optimal to high-normal groups. In contrast, effective renal plasma flow remained constant. Albuminuria was similar in all groups. Of interest, the proportion of subjects with concentric pattern of cardiac geometry (relative wall thickness ≥0.44) increased from 7% in optimal to 13% and 20% in normal and high-normal groups, respectively ( P <0.05). Within this normotensive range of blood pressure, left ventricular mass index and relative wall thickness but not albuminuria were linearly correlated to systolic blood pressure; however, no correlation with diastolic blood pressure was found. In conclusion, changes in cardiac geometry and renal hemodynamics (increase in glomerular filtration rate and filtration fraction, an approximate index of glomerular pressure) that could predispose to cardiovascular morbidity and renal risk are already present in normotensive subjects with blood pressure higher than 120/80 mm Hg.