Earlier studies have demonstrated that an impaired capacity to increase heart rate (HR) and a slowed HR recovery following exercise are both associated with cardiovascular mortality. We sought to determine whether HR profiles during exercise testing are superior to respiratory gas parameters in predicting mortality among patients with cardiac disease. Five-hundred and fifty stable cardiac patients (63.4 +/- 9.9 years) underwent a symptom-limited incremental exercise test. Measurements included peak VO(2), VE/VCO(2) slope, HR increase (HR difference from rest to peak exercise), and HR recovery (HR difference from peak to 2 minutes after exercise). Twenty-eight cardiovascular-deaths occurred during 4 years of prospective follow-up. In multivariate analysis, the CPX parameters were found to be significant predictors of cardiovascular-death; peak VO(2) (relative risk (RR), 3.44; 95% CI 1.37 to 8.62; P = 0.008), VE/VCO(2) slope (RR, 1.52; 95% CI 1.11 to 2.08; P = 0.009), while HR increase and HR recovery were determined not to be independent predictors. Although HR profiles during exercise testing are easy to perform and useful as prognostic predictors in patients with cardiac disease, they are not superior to respiratory gas analysis.