Heart Rate Response to Exercise Stress Testing in Asymptomatic Women The St. James Women Take Heart Project

Background-The definition of a normal heart rate (HR) response to exercise stress testing in women is poorly understood, given that most studies describing a normative response were predominately based on male data. Measures of an attenuated HR response (chronotropic incompetence) and age-predicted HR have not been validated in asymptomatic women. We investigated the association between HR response to exercise testing and age with prognosis in 5437 asymptomatic women. Methods and Results-Participants underwent a symptom-limited maximal stress test in 1992. HR reserve (change in HR from rest to peak), chronotropic index, and age-predicted peak HR were calculated. Deaths were identified to December 31, 2008. Mean age at baseline was 52 +/- 11 years, with 549 deaths (10%) over 15.9 +/- 2.2 years. Mean peak HR was inversely associated with age; mean peak HR = 206-0.88(age). After adjusting for exercise capacity and traditional cardiac risk factors, risk of death was reduced by 3% for every 1-beat-per-minute increase in peak HR, and by 2% for every 1-beat-per-minute increase in HR reserve (P < 0.001). Inability to achieve 85% age-predicted HR was not an independent predictor of mortality, but being >= 1 SD below the mean predicted HR or a chronotropic index < 0.80 based on the prediction model established by this cohort were independent predictors of mortality (P < 0.001 and P = 0.023, respectively). Conclusions-Chronotropic incompetence is associated with an increased risk of death in asymptomatic women; however, the traditional male-based calculation overestimates the maximum HR for age in women. Sex-specific parameters of physiological HR response to exercise should be incorporated into clinical practice. (Circulation. 2010; 122: 130-137.)