Slow heart rate recovery (HRR) from a graded exercise treadmill test (GXT) is a marker of impaired parasympathetic reactivation associated with elevated mortality in patients symptomatic for coronary heart disease (CHD). Little is known about changes in HRR over time in adults free from CHD, or about demographic, behavioral, and clinical factors associated with the development of slow HRR.
PURPOSE: To describe change in HRR over 20 years, and test the hypothesis that participants with less favorable CHD risk factors during young adulthood are more likely to develop slow HRR over follow-up.
METHODS: Participants from the Coronary Artery Risk Development in Young Adults (CARDIA) study who were aged 18 to 30 years in 1985–86 underwent symptom-limited maximal GXT using a modified Balke protocol at the baseline and 20-year (2005-06) examinations. HRR was calculated as the difference between maximum heart rate (HR) and HR 2 minutes following cessation of the GXT in 2,556 participants (56% female, 44% black). Slow HRR was defined as 2-minute HRR < 22 beats/min (bpm).
RESULTS: After excluding 56 participants (2.2%) with slow HRR at baseline, mean HRR was 43 bpm (SD = 11). Over 20 years, HRR declined to 39 bpm (SD = 12) and incident slow HRR occurred in 142 participants (5.7%). In a multivariable model adjusting for GXT duration and maximum HR, only low education, smoking, BMI and high blood pressure were significantly associated with incident slow HRR (Table). There were no differences in the incidence of slow HRR by sex and race when GXT performance was taken into account.
CONCLUSIONS: HRR declines with aging in all asymptomatic adults, but the 20-year incidence of clinically slow HRR is most strongly associated with traditional CHD risk factors.