Clinical predictors of exercise capacity 1 year after cardiac transplantation

Background: The exercise capacity of cardiac transplant recipients is reduced compared with normal controls. However, clinical variables predictive of post-transplant exercise capacity have not been well defined. The objective of the present study was to identify clinical features predictive of post-transplant exercise capacity. Methods: Ninety-five cardiac transplant recipients underwent cardiopulmonary testing at 1 year after transplant. The exercise parameters were compared with both pre-transplant values and normal subjects. The relationships between exercise parameters and clinical characteristics were analyzed. Results: Mean peak oxygen consumption (VO₂) and exercise test duration at 1-year post-transplant improved significantly from 16.4 to 19.9 ml/kg/min and 5.5 to 7.6 minutes, respectively (p < 0.001), but were significantly lower than for normal controls (peak VO₂ 34.0 ml/kg/min; exercise duration 11.2 minutes; p < 0.001). Age- and gender-adjusted VO₂ was 54% of predicted. Pre-operative body weight correlated strongly with post-transplant weight (r = 0.80, p < 0.001). Significant recipient predictors of 1-year post-transplant peak VO₂ identified by multivariate regression analysis were age, male gender, body mass index, exercise peak heart rate and duration of post-operative intensive care. Donor variables did not contribute significantly to post-transplant peak VO₂. Conclusions: Peak VO₂ improved after cardiac transplantation but remained significantly impaired compared with normal subjects. In estimating the impact of cardiac transplantation on exercise capacity the most important pre-transplant factors to consider are age, gender and height and weight (or, alternatively, body mass index).