Decreased blood pressure variability at rest in patients with primary aldosteronism.

Increased blood pressure (BP) variability in essential hypertension (EH) is attributed in part to a reduction in baroreflex sensitivity. We previously showed that baroreflex sensitivity is not reduced in hypertension associated with primary aldosteronism (PA) compared with normotensive (NT) subjects. This study examined whether the preservation of baroreflex function in patients with PA would prevent an increase in BP variability. The beat-to-beat BP (measured with Finapres) and RR interval (from electrocardiograms) were monitored for 10 min in the supine and standing positions in 34 patients with PA, 60 patients with EH, and 45 NT subjects. Recordings were also performed during mild ergometer 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 assessed by the closed-loop gain between systolic BP and RR interval variability. 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 patients with EH in both supine and standing positions. The SD of SBP and DBP were similar in patients with PA and NT subjects, although the CV were significantly smaller in patients with PA. The BRS was inversely correlated with both the SD and CV for SBP 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 during exercise, compared with rest, in the PA and NT groups but was decreased (P < .05) in the patients with EH. In conclusion, primary aldosteronism is characterized by decreased supine and standing BP variability, which is due in part to the preservation of baroreflex function. Our data further showed that BP variability is minimized by nonbaroreflex mechanisms during mild exercise.