Exercise capacity and cardiac allograft ischemic time in recent heart transplant recipients

Abstract

Background: Prolonged ischemic times (IT) for transplant hearts transported under cold storage conditions are associated with an increased risk of mortality; however, the impact of IT on functional outcomes, such as exercise capacity (EC), is not fully understood. This prospective, observational cohort study aimed to determine the association between EC, a strong predictor for post-transplant survival, and relatively longer IT. Methods: Thirty heart transplant recipients were grouped dichotomously according to relatively longer (>180 minutes) or shorter (≤180 minutes) IT. A cardiopulmonary exercise test (CPET) was performed post-transplant upon cardiac rehabilitation admission, during which EC [peak volume of oxygen consumption (VO2)] and CPET duration were measured and compared between groups. Results: This cohort was predominantly male (n = 22, 73%) with a median age of 57.5 years [Q1-Q3: 54.0-65.0]. Baseline demographics and characteristics were similar between groups aside from United Network for Organ Sharing listing status, in which patients listed as status 1 or 2 were more likely to have long IT. Twelve (40%) participants received a donor heart with long IT. Surprisingly, higher peak VO2 was observed in those with long (15.0±2.8) than short (13.1±3.7) IT (p = 0.009). However, CPET duration was significantly shorter in recipients with a long IT (6.3 vs 7.7 minutes, p = 0.048) despite similar time since transplant, ratings of perceived exertion, protocol performed, and EC. Conclusions: In this modest-sized cohort, EC was higher in heart transplant recipients with donor IT >180 minutes compared with those with IT ≤180 minutes. However, CPET duration was significantly shorter in those with relatively longer IT.

Keywords

• exercise test
• heart transplantation
• oxygen consumption
• cold ischemia
• tissue and organ procurement