PRE-HYPERTENSION IS STRONGLY ASSOCIATED WITH DELAYED HEART-RATE RECOVERY DURING EXERCISE STRESS TEST

Abstract

Background: Heart rate recovery (HRR), a marker of parasympathetic cardiac function predicts cardiovascular disease mortality. HRR is known to be reduced in hypertension but its association with prehypertension is rarely studied. Methods: The study population consisted of 710 asymptomatic individuals (90% men, 47 + 7.9 years). HRR was defined as the difference between peak heart rate (HR) & HR after a 2 minute rest. Prehypertension (PHT) was categorized into stage I (systolic BP 120-129mmHg or Diastolic BP 80-84mmHg) or stage II (SBP 130-139mmHg or DBP 85-89mmHg). Results: The prevalence for PHT was 40% for stage I and 14% for stage II. The mean HRR was slower in the PHT groups than in normotensives (60 bpm & 58 bpm in stage I and II PHT vs. 65bpm in normal BP p <0.01). These differences remained significant even after adjusting for cardiovascular risk factors. In addition, persons with PHT were more likely to be in the lowest quartile of HRR compared to those with normal BP (adjusted OR 3.80 CI 1.06, 13.56 for stage II and 3.01 CI 1.05, 8.66 for Stage I PHT). Conclusion: In this population, degrees of prehypertension are independently associated with delayed HRR, suggesting early autonomic dysfunction in the development of hypertension. Further studies are needed to determine the direction of this association and the optimal management strategies.