Prognostic Value of Exercise Stress Echocardiography in Pediatric Cardiac Transplant Recipients

Abstract

Cardiac allograft vasculopathy (CAV) is a leading cause of long-term morbidity and mortality in pediatric heart transplant (HTx) recipients. Exercise stress echocardiography (ESE) has been shown to be useful in the detection of angiographically confirmed coronary artery disease in children. However, the prognostic utility of ESE for prediction of cardiac events in HTx survivors is unknown. We aim to assess whether an abnormal (positive) ESE is be associated with a higher risk of future cardiovascular (CV) outcomes in pediatric HTx recipients. We conducted a retrospective review of CV outcomes in a cohort of 95 pediatric HTx recipients who underwent 188 ESEs over a 10-year period. A composite endpoint for CV events including myocardial infarction, hospitalization for nonrejection heart failure, coronary revascularization, need for repeat transplantation, and death was used. Based on the interpretation of the ESE results, each ESE study was classified for this study as either positive (abnormal) or negative (normal) for ischemia. Results of the coronary angiograms performed near the time of ESE were also assessed and classified for this study as positive (abnormal) or negative (normal) for CAV according to standard HTx criteria for CAV. Fifty-one (27%) ESEs were positive for ischemia. There was a total of 35 CV events in 23 patients. A positive ESE was associated with increased risk of any CV event (hazard ratio=3.55; 95% CI, 1.52, 8.28), as well as an increased risk of CV death (hazard ratio=3.19; 95% CI, 1.23, 8.28). Freedom from composite CV outcome at 1, 2, and 3years following a positive ESE was 89.9% (95% CI=77.3%, 95.7%), 81.5% (95% CI=65.9%, 90.5%), and 63.2% (95% CI=41.9%, 78.5%), respectively. Freedom from composite CV outcome at 1, 2, and 3years following a negative ESE was 99.3% (94.8, 99.9), 98.4% (93.6, 99.6), and 97.0% (90.6, 99.1), respectively. No patient died within 1year of a negative ESE. In this largest study of ESE in pediatric HTx recipients, a positive or abnormal ESE is associated with increased future CV morbidity and mortality. Conversely, a negative ESE can help predict CV event-free survival. Even in the setting of a normal coronary angiogram, our pilot data show that an abnormal ESE may still be clinically important. Use of ESE in follow-up may improve risk stratification and management of pediatric HTx recipients.