Association of exercise capacity and the heart rate profile during exercise stress testing with subclinical coronary atherosclerosis: data from the Heinz Nixdorf Recall study

Exercise capacity and heart rate profile parameters obtained from exercise stress testing as well as the subclinical coronary atherosclerosis burden from cardiac CT have been suggested to improve cardiovascular (CV) risk stratification beyond traditional risk factors (RF) in persons at risk of CV events. To study the association of exercise stress-test variables with the coronary artery calcium (CAC) burden in relation to age, sex and traditional RF in subjects without known coronary artery disease from the general population. In 3,163 subjects, CV and RF were measured, a bicycle stress test was performed and the electron beam CT-based CAC-Agatston score was quantified. Exercise capacity, chronotropic response and an abnormal HR recovery were significantly and inversely related to CAC scores in men and women in univariate unadjusted analysis. This association was diminished after adjustment for age and sex and further after adjustment for traditional risk factors. In multivariate analysis, chronotropic response in men [estimate (95% CI): 0.94 (0.91-0.97), P = 0.0005] and an abnormal HR recovery (< 15 bpm after 1 min) in women [estimate: 1.34 (1.07-1.70), P = 0.013] but not exercise capacity remained associated with CAC independent of traditional RF. In subjects not taking lipid-lowering, antiarrhythmic or antihypertensive drugs, estimates for the observed associations were essentially unchanged. The clinical ability of these variables to predict a high CAC score was limited. The strong inverse association of exercise capacity, chronotropic response and abnormal HR recovery during exercise stress testing with the CAC burden in unadjusted univariate analysis is largely influenced by age, sex and cardiovascular RFs. The degree, to which exercise stress-test variables and the CAC burden independently contribute to the prediction of cardiovascular events, remains to be shown.