Diastolic Function Unchanged After Lifestyle Intervention Despite Improved VO₂ in Pediatric Heart Transplant Patients

Pediatric heart transplant recipients commonly exhibit diastolic dysfunction, which may contribute to reduced exercise capacity. In our Healthy Hearts study, a supervised exercise and nutrition intervention improved exercise performance and endothelial function. We hypothesized that this intervention would also improve resting echocardiographic markers of diastolic function in this cohort. Fourteen stable heart transplant patients aged 8 to 19 years, at least one year post-transplant, participated in a live-video-supervised exercise and nutrition intervention from 2014 to 2018. Participants completed a 12-16-week intervention, followed by a maintenance phase of similar duration with mostly self-directed sessions. Echocardiograms taken near baseline, post-intervention, and post-maintenance visits were reviewed retrospectively. Diastolic dysfunction at baseline was defined by any of the following: E/A ratio > 2, mitral deceleration time < 160 ms, septal or lateral E/e' > 14, or tricuspid regurgitant jet velocity > 2.8 m/s. Atrial strain was measured using TOMTEC software. No significant improvements from baseline to post-intervention were observed in conventional diastolic function parameters or atrial strain, including patients with baseline diastolic dysfunction (n = 9). Among those with baseline diastolic dysfunction, there was a strong inverse correlation between the change in E/A ratio and the change in peak VO₂ from baseline to post-intervention (r = - 0.94). Despite improvements in exercise capacity and endothelial function following a nutrition and exercise intervention in pediatric heart transplant patients, echocardiographic markers of diastolic function remained unchanged. These findings suggest that peripheral rather than cardiac adaptations may underlie the observed functional improvements.