Oxygen Consumption at Anaerobic Threshold Predicts Cardiac Events After Heart Transplantation.

OBJECTIVES

The ventilatory efficiency and functional capacity measured by the cardiopulmonary exercise test (CPET) have been used as important prognostic variables in congestive heart failure. This study sought to identify whether these predictors before heart transplantation (HTX) play a key role in predicting adverse events in patients with heart failure after HTX.

METHODS

This was a retrospective cohort study design. HTX recipients were included for analysis. Ventilation to carbon dioxide production slope (VE/VCO2 slope) and oxygen consumption (VO2) during exercise were collected by CPET, which represented ventilator efficiency and functional capacity respectively. Cardiac-related events 2 years after HTX were recorded by chart review. We divided patients into 2 groups based on VE/VCO2 slope = 34, peak VO2 = 14 mL/kg/min and VO2 at aerobic threshold (AT) = 11 mL/kg/min. Kaplan-Meier survival curves was used to represent the events rate between groups and Log rank test was used to test significance.

RESULTS

A total of 87 patients after HTX were included. Mean (SD) age was 48 (11) years and 73 were male; 28 subjects suffered from events, and 76 cardiac events were recorded. The mean (SD) data of peak VO2, VO2 at AT, and VE/VCO2 slope analyzed from CPET were 17.8 (5.6) mL/kg/min, 15.4 (4.4) mL/kg/min, and 33.1 (8.2) mL/kg/min, respectively. Lower VO2 at AT contributed to increase events rate (P < .05).

CONCLUSION

Aerobic capacity may better predict 2-year cardiac events in patients after HTX. Strategies to improve aerobic capacity should be focused on in the cohort.