Exercise capacity in early and late adult heart transplant recipients

Background: The aim of this study was to compare peak oxygen consumption (VO2), heartrate (HR) reserve and HR recovery in early and late heart transplant recipients. Moreover, wealso aimed to correlate peak VO2 and HR reserve.Methods: Fivteen heart transplant recipients (8 early and 7 late), 8 ± 3 and 161 ± 58 monthsafter transplantation, respectively, performed a cardiopulmonary exercise test.Results: Early heart transplant recipients showed lower HR reserve compared to late heart transplantrecipients, 39 ± 15 vs. 58 ± 19 bpm (p = 0.049), respectively. Peak VO2 (23.4 ± 4 vs. 21.8 ± 5 mL/kg/min, p = 0.56), VO2 respiratory compensation point (18.7 ± 2 vs. 18.5 ± 4 mL//kg/min, p = 0.48) and time of exercise testing (14 ± 3 vs. 13 ± 3 min, p = 0.95) %age--predicted peakVO2 (65 ± 12 vs. 70 ± 10%, p = 0.24) were not different between the groups.Moreover, peak VO2 and %age-predicted peakVO2 correlated with HR reserve only in early hearttransplant recipients (r = 0.89, p = 0.003 and r = 0.71, p = 0.04, respectively). Early hearttransplant recipients increased HR (2.5 ± 2.0% at fi rst minute and 0.7 ± 2.3% at the secondminute), while late recipients decreased HR (–6.0 ± 4.7 at fi rst minute and –15.5 ± 2.4 at thesecond minute) at the recovery period of cardiopulmonary exercise test.Conclusions: Exercise capacity did not show difference between early and late heart transplantrecipients. HR reserve was higher in late compared to early recipients. HR reserve onlycorrelated with peak VO2 in early recipients. Moreover, only late heart transplant recipientsshowed decrease in HR during the recovery period of cardiopulmonary exercise test