Prognostic impact of peak oxygen uptake and heart rate reserve in patients after off‐pump coronary artery bypass grafting

BACKGROUND Peak oxygen uptake (peak VO2 ) and heart rate reserve (HRR) are independent prognostic markers of cardiovascular disease. However, the impact of peak VO2 and HRR on long-term prognosis after off-pump coronary artery bypass grafting (OP-CABG) remains unclear. HYPOTHESIS To determine the prognostic impact of peak VO2 and HRR in patients after OP-CABG. RESULTS We enrolled 327 patients (mean age, 65.1 ± 9.3 years; male, 80%) who underwent OP-CABG and participated in early phase II cardiac rehabilitation. All participants underwent cardiopulmonary exercise testing (CPET) at the beginning of such rehabilitation. Overall, 48 (14.6%) patients died during the median follow-up period of 103 months. The non-survivor had significantly lower levels of peak VO2 (10.6 ± 0.5 vs. 13.7 ± 0.2 ml/kg/min, p < .01) and HRR (24.2 ± 1.8 vs. 32.7 ± 0.8 beats/min, p < .01) than the survivor. In both groups, peak VO2 significantly correlated with HRR (p < .01). Moreover, patients were divided into four groups according to the peak VO2 and HRR levels for predicting total mortality. The low-peak VO2 /low-HRR group had a significantly higher mortality risk than the other groups (hazards ratio, 5.61; 95% confidence interval, 2.59-12.16; p < .01). After adjusted the confounding factors, peak VO2 and HRR were independently associated with total mortality (both p < .05). CONCLUSIONS HRR is a simple parameter of CPET and an important prognostic marker for the risk stratification of total mortality even in patients with low-peak VO2 after OP-CABG.