Kuopio Research Institute of Exercise Medicine, Kuopio, Finland Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital, Kuopio, Finland Information Technology Center, University of Eastern Finland, Kuopio Campus, Finland Department of Medicine, Kuopio University Hospital, Kuopio, Finland Institute of Biomedicine/Physiology, University of Eastern Finland, Kuopio Campus, Finland Institute of Public Health and Clinical Nutrition, University of Eastern Finland, Kuopio Campus, Finland Lapland Central Hospital, Rovaniemi, Finland.
Background: A slow heart rate recovery (HRR) after an exercise test is associated with an increased risk of all-cause mortality in asymptomatic individuals, but the data regarding additional prognostic information provided by HRR beyond other exercise test variables are inconsistent. We investigated the prognostic significance of HRR for premature death, particularly in relation to other exercise test variables. Methods: The study subjects were a representative population-based sample of 1102 men (42-61 years of age) without cardiovascular disease, cancer or diabetes. HRR was defined as the difference between maximal heart rate and heart rate 2 min after a maximal symptom-limited exercise test using a cycle ergometer. The association between HRR and premature mortality was examined with Cox regression models. Results: During an average follow-up of 18 years, 238 deaths occurred. HRR was an independent predictor of death (for a decrease of 12 beats/min, relative risk [RR] 1.16, 95% CI 1.02-1.33, P=0.02) after adjustment for age and established risk factors. When added in a Cox model with chronotropic response (decrease of 12 beats/min, RR 1.09, 95% CI 0.93-1.27, P=0.26) or cardiorespiratory fitness (decrease of 12 beats/min, RR 1.12, 95% CI 0.98-1.30, P=0.08), the association between a slow HRR and an increased risk of death was clearly weaker. Conclusion: A slow 2-min HRR after a cycle ergometer exercise test was an independent predictor of death in healthy middle-aged men after accounting for demographic and clinical characteristics. However, it was no longer predictive after accounting for chronotropic response and exercise capacity.