Improvement in cardiac function but not structure in adults born preterm following a prescribed moderate to high intensity exercise intervention: a randomized clinical trial

Abstract Background People born preterm (<37 weeks’ gestation) have a potentially adverse cardiac phenotype that progresses with blood pressure elevation and may explain their increased risk of early heart failure and cardiovascular-related mortality. It remains unknown whether lifestyle or pharmacological interventions lead to beneficial left ventricle (LV) and right ventricle (RV) structural and/or functional changes in preterm-born adults. Purpose To determine whether preterm-born adults with elevated and stage 1 hypertension exhibit similar cardiac remodelling following a 16-week aerobic exercise intervention as their term-born peers with comparable blood pressures. Methods We conducted an open, parallel, two-arm superiority randomised controlled (1:1) trial in n=203 adults aged 18-35 years old with elevated or stage 1 hypertension. Participants were randomised to a 16-week aerobic exercise intervention targeting three, 60-minute supervised sessions per week at 60-80% peak heart rate (exercise intervention) or sign-posted to educational materials (controls). In a pre-specified cardiovascular magnetic resonance imaging (CMR) sub-study in n=100 individuals, CMR was performed before and after the 16-week intervention. Group differences in outcome variables after the intervention were examined using ANCOVA adjusting for baseline outcome variables, sex, and age. Interactions between birth category and intervention effect were investigated by including an interaction term in the intervention ANCOVA analyses. Results One hundred participants completed CMR scans at baseline and after the 16-week intervention, with n=47 in the exercise intervention group (n=26 term-born; n=21 preterm-born) and n=53 controls (n=32 term-born; n=21 preterm-born). Cardiac structural measures in preterm-born adults did not change following the intervention. However, term-born adults in the exercise intervention group decreased LV mass to end-diastolic volume ratio (adjusted mean difference: -0.03, 95% CI: -0.06,-0.01, interaction term p=0.027) and increased RV stroke volume (adjusted mean difference: 5.53mL/m2, 95% CI: 2.60,8.47, interaction term p=0.076) versus controls. Preterm-born adults in the exercise intervention group increased LV basal- and mid-ventricular circumferential strain versus controls (adjusted mean difference: -1.33%, 95% CI: -2.07,-0.60, interaction term p=0.057 and adjusted mean difference: -1.54%, 95% CI: -2.46,-0.63, interaction term p=0.046, respectively), which was not observed in term-born adults. Similarly, preterm-born adults improved RV longitudinal strain versus controls (adjusted mean difference: -0.51%, 95% CI: -1.49,0.46, interaction term p=0.053), which was also not observed in term-born adults. Conclusions Aerobic exercise training improves myocardial function but not cardiac structure in preterm-born adults. Modified exercise protocols or combination with pharmacological intervention may lead to additional cardiac remodelling benefits.