Is there a relationship between heart rate recovery and blood pressure in white coat hypertension?

Aim    Increasing evidence suggests that autonomic dysfunction may be involved in the etiology of white coat hypertension (WCH). The aim of this study was to evaluate cardiac autonomic function by using heart rate recovery (HRR) indices in patients with WCH classified according to their circadian rhythm type of blood pressure (BP).Material and methods    This cross-sectional study included 120 participants over the age of 18 yrs, including 50 patients diagnosed with WCH and 70 healthy controls with normal in- and out-of-office BP and without any known disease. Circadian rhythm types, i.e., dippers and non-dippers, were identified using ambulatory BP monitoring. The HRR indices were calculated by subtracting the 1st-minute (HRR1), 2nd-minute (HRR2), and 3rd-minute (HRR3) heart rates from the maximal heart rate recorded during stress testing.Results    The lesser decline in nighttime BP (6.4±2.14 and 13.3±2.2 mmHg, respectively; p<0.001) and the smaller mean HRR1 (25.5±3.0 and 30.3±3.1 beats / min, respectively; p<0.001) were evident in WCH non-dippers compared to WCH dippers. Linear regression analysis showed that HRR1 (β±SE=0.43±0.11; p<0.001) and diastolic BP at maximum exercise (β±SE=0.14±0.07; p=0.040) are independent risk factors for the blunted decline in nighttime BP.Conclusion    Delayed recovery of heart rate after an exercise stress test is associated with non-dipper type of circadian rhythm of BP. This was more pronounced in WCH patients, and these patients are at risk of autonomic dysfunction.