Abstract
The aim of the present cross-sectional study was to evaluate heart rate recovery (HRR) in normotensive and hypertensive individuals with either nondipper or dipper type circadian rhythm of blood pressure. Eighty-five patients were divided into 4 groups according to the presence of hypertension and pattern of circadian blood pressure as follows: (1) normotensive/dipper, n=20; (2) normotensive/nondipper, n=21; (3) hypertensive/dipper, n=22; and (4) hypertensive/nondipper, n=22. HRR indices were calculated by subtracting first, second, and third minute heart rates from the maximal heart rate obtained during stress testing and designated as HRR1, HRR2, and HRR3. Mean HRR1 values (29.7+/-4.0 vs 26.6+/-3.7, P=.016) were significantly higher in the normotensive/dipper group than the normotensive/nondipper group. Mean HRR1 values (28.6+/-4.0 vs 24.8+/-4.6 beats per minute, P=.007) were higher in the hypertensive/dipper group than the hypertensive/nondipper group. Spearman's correlation analyses revealed a positive correlation between degree of nighttime dipping and HRR1 (r=.600, P=.001). The correlation coefficient between degree of nighttime dipping and HRR1 was higher in the hypertensive group than the normotensive group (r=.676, P=.001 and r=.575, P=.001, respectively). Blunting of the nocturnal fall in blood pressure associates with a delayed recovery of heart rate after graded maximal exercise in both normotensive and hypertensive groups.