DECREASED BLOOD-PRESSURE VARIABILITY AT REST IN PATIENTS WITH PRIMARYALDOSTERONISM

Increased blood pressure (BP) variability in essential hypertension (E H) is attributed in part to a reduction in baroreflex sensitivity. We previously showed that baroreflex sensitivity is not reduced in hypert ension associated with primary aldosteronism (PA) compared with normot ensive (NT) subjects. This study examined whether the preservation of baroreflex function in patients with PA would prevent an increase in B P variability. The beat-to-beat BP (measured with Finapres) and RR int erval (from electrocardiograms) were monitored for 10 min in the supin e and standing positions in 34 patients with PA, 60 patients with EH, and 45 NT subjects. Recordings were also performed during mild ergomet er exercise in 7 PA patients, 8 EH patients, and 9 NT subjects. Blood pressure variability was assessed by both standard deviation (SD) and coefficient of variation (CV). Baroreflex sensitivity (BRS) was assess ed by the closed-loop gain between systolic BP and RR interval variabi lity. The SD and the CV of systolic BP (SBP) and the CV of diastolic ( DBP) BP were significantly smaller in patients with PA than in patient s with EH in both supine and standing positions. The SD of SEP and DBP were similar in patients with PA and NT subjects, although the CV wer e significantly smaller in patients with PA. The BRS was inversely cor related with both the SD and CV for SEP in the supine (r = -0.397 and -0.440, P <.05, respectively) and standing (r = -0.457 and -0,412, P < .05, respectively) positions in patients with PA. Exercise reduced the BRS in all groups (70%, 26%, and 64% for PA, EH, and NT, respectively , P <.01). Blood pressure variability did not change significantly dur ing exercise, compared with rest, in the PA and NT groups but was decr eased (P <.05) in the patients with EH. In conclusion, primary aldoste ronism is characterized by decreased supine and standing BP variabilit y, which is due in part to the preservation of baroreflex function. Ou r data further showed that BP variability is minimized by nonbarorefle x mechanisms during mild exercise. Am J Hypertens 1998;11:828-838 (C) 1998 American Journal of Hypertension, Ltd.