Increased Heart Rate Responsiveness after Heart Transplant is Associated with Increased Peak Oxygen Consumption and Treadmill Time in CPET

Abstract

Introduction Chronotropic incompetence is very common after heart transplant. The extent to which it affects the functional capacity of heart transplant patients is unknown. We hypothesize that a higher heart rate responsiveness would be associated with improved peak oxygen uptake and may have long-term prognostic impact. Methods We performed a retrospective analysis of all patients who underwent heart transplantation and cardiopulmonary exercise testing (CPET) in the first post-transplant year at a single large academic center between the year 2000 and 2011. Peak VO2 and total exercise time were assessed by CPET. Heart rate responsiveness was defined as the difference between peak and resting heart rate during CPET. The association of heart rate responsiveness with peak VO2 and total exercise time was analyzed using multivariable linear regression, and survival analysis was performed via a cox proportional hazard model. Results CPET was performed at our institution in 271 patients during the first year post heart transplantation at a median of 2.3 months. Subjects were 82% male, age 55 (IQR 45-61) at time of CPET. After multivariate adjustment, each ten beat/min increase in heart rate responsiveness was associated with a 0.9 ml/kg/min increase in peak oxygen consumption (p Conclusions Chronotropic incompetence after heart transplant is associated with decreased functional capacity but is not a prognostic indicator of mortality after transplant.