Early Cardiopulmonary Fitness after Heart Transplantation as a Determinant of Post-Transplant Survival

Background: Decreased peak oxygen consumption during exercise (peak Vo₂) is a well-established prognostic marker for mortality in ambulatory heart failure. After heart transplantation, the utility of peak Vo₂ as a marker of post-transplant survival is not well established. Methods and Results: We performed a retrospective analysis of adult heart transplant recipients at the Hospital of the University of Pennsylvania who underwent cardiopulmonary exercise testing within a year of transplant between the years 2000 to 2011. Using time-to-event models, we analyzed the hazard of mortality over nearly two decades of follow-up as a function of post-transplant percent predicted peak Vo₂ (%Vo₂). A total of 235 patients met inclusion criteria. The median post-transplant %Vo₂ was 49% (IQR 42 to 60). Each standard deviation (±14%) increase in %Vo₂ was associated with a 32% decrease in mortality in adjusted models (HR 0.68, 95% CI 0.53 to 0.87, p = 0.002). A %Vo₂ below 29%, 64% and 88% predicted less than 80% survival at 5, 10, and 15 years, respectively. Conclusions: Post-transplant peak Vo₂ is a highly significant prognostic marker for long-term post-transplant survival. It remains to be seen whether decreased peak Vo₂ post-transplant is modifiable as a target to improve post-transplant longevity.