Improvement in myocardial deformation but not structural indices in adults born preterm following a prescribed aerobic exercise intervention: a randomized clinical trial

Background People born preterm (<37 weeks’ gestation) have a potentially adverse cardiac phenotype that progresses with blood pressure elevation. We sought to determine whether preterm-born adults with elevated and stage 1 hypertension exhibit similar cardiac structural and functional remodeling following a 16-week aerobic exercise intervention as their term-born peers. Methods We conducted an open, parallel, two-arm superiority randomized controlled (1:1) trial in n=203 adults aged 18-35 years old with elevated or stage 1 hypertension. Participants were randomized to a 16-week aerobic exercise intervention targeting three, 60-minute supervised sessions per week at 60-80% peak heart rate (exercise intervention group) or sign-posted to educational materials on hypertension and recommended lifestyle behaviors (control group). In a pre-specified cardiovascular magnetic resonance imaging (CMR) sub-study, CMR was performed on a 3.0-Tesla Siemens scanner to assess left ventricular (LV) and right ventricular (RV) structure and function before and after the 16-week intervention period. Group differences in outcome variables after the intervention were examined using analysis of covariance (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 both 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). There was a significantly different response to the exercise intervention between preterm- and term-born participants. In term-born participants, LV mass to end-diastolic volume ratio decreased (adjusted mean difference: -3.43, 95% CI: -6.29,-0.56, interaction term p=0.027) and RV stroke volume index increased (adjusted mean difference: 5.53mL/m 2 , 95% CI: 2.60,8.47, interaction term p=0.076) for those in the exercise intervention group versus controls. No significant effects were observed for cardiac structural indices in preterm-born participants. In preterm-born participants, LV basal- and mid-ventricular circumferential strain increased (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) and RV global longitudinal strain increased (adjusted mean difference=-1.99%, 95% CI=-3.12,-0.87, interaction p=0.053) for those in the exercise intervention group versus controls. No significant effects were observed for myocardial deformation parameters in term-born participants. Conclusions Aerobic exercise training induces improved myocardial function but not cardiac structure in preterm-born adults.