Characteristics of Cardiopulmonary Exercise Tests in Heart Transplantation Patients: The Importance of Chronotropic Incompetence in Predicting Exercise Capacity

Purpose The response of the transplanted heart to exercise differs from that of the native heart for many reasons, one of which is autonomic denervation, which may be associated with chronotropic incompetence (CI). We assessed cardiopulmonary exercise capacity in heart transplantation (HT) patients with the aim to identify clinical, hemodynamic and ECHO parameters associated with exercise capacity. Methods The study population comprised 70 HT patients who had undergone cardiopulmonary exercise tests at the same time as ECHO and right heart study. Good functional exercise capacity was defined as peak oxygen uptake (VO2peak) >60% of the general population (good vs low functional capacity). Age-predicted maximal heart rate (APMHR) was calculated as 164 - 0.7(age). Heart rate reserve (HRR) was defined as HRpeak - HRrest; age-predicted HRR (APHRR) as APMHR - HRrest; and CI as failure to achieve >62% of APHRR. Adjusted HRR was calculated as HRR/APHRR. Results Average VO2peak was 21 mL/kg -1 min -1 corresponding to 72% of predicted. The prevalence of CI was 19%. Both adjusted HRR (r=0.46 P Conclusion The ability to perform physical activity, an important determinant of quality of life, is enabled by an increase in oxygen uptake. In this study, CI was the only independent predictor of exercise intolerance in HT patients. Lower resting HR was associated with a higher risk for CI.