Impaired myocardial reserve underlies reduced exercise capacity and heart rate recovery in preterm-born young adults

Abstract

Aims We tested the hypothesis that the known reduction in myocardial functional reserve in preterm-born young adults is an independent predictor of exercise capacity (peak VO2) and heart rate recovery (HRR). Methods and results We recruited 101 normotensive young adults (n = 47 born preterm; 32.8 ± 3.2 weeks’ gestation and n = 54 term-born controls). Peak VO2 was determined by cardiopulmonary exercise testing (CPET), and lung function assessed using spirometry. Percentage predicted values were then calculated. HRR was defined as the decrease from peak HR to 1 min (HRR1) and 2 min of recovery (HRR2). Four-chamber echocardiography views were acquired at rest and exercise at 40% and 60% of CPET peak power. Change in left ventricular ejection fraction from rest to each work intensity was calculated (EFΔ40% and EFΔ60%) to estimate myocardial functional reserve. Peak VO2 and per cent of predicted peak VO2 were lower in preterm-born young adults compared with controls (33.6 ± 8.6 vs. 40.1 ± 9.0 mL/kg/min, P = 0.003 and 94% ± 20% vs. 108% ± 25%, P = 0.001). HRR1 was similar between groups. HRR2 decreased less in preterm-born young adults compared with controls (−36 ± 13 vs. −43 ± 11 b.p.m., P = 0.039). In young adults born preterm, but not in controls, EFΔ40% and EFΔ60% correlated with per cent of predicted peak VO2 (r2 = 0.430, P = 0.015 and r2 = 0.345, P = 0.021). Similarly, EFΔ60% correlated with HRR1 and HRR2 only in those born preterm (r2 = 0.611, P = 0.002 and r2 = 0.663, P = 0.001). Conclusions Impaired myocardial functional reserve underlies reductions in peak VO2 and HRR in young adults born moderately preterm. Peak VO2 and HRR may aid risk stratification and treatment monitoring in this population.

Association of Systolic Blood Pressure Elevation With Disproportionate Left Ventricular Remodeling in Very Preterm-Born Young Adults

“…4 Human studies from birth through to young adulthood have now demonstrated that LV function and structure are altered in individuals born preterm, 3 including an inability to meet the demands of physiologic stress in adolescence and young adulthood. 6,7,19,20 The lower myocardial functional reserve seen in preterm-born young adults in response to acute stress may in part explain why the risk of early heart failure is so much greater in this population. 1,21 Given the underlying morphologic impairments in the preterm heart, it is conceivable that blood pressure elevation would have a greater effect on cardiac remodeling in this population.…”

Impact of the Vulnerable Preterm Heart and Circulation on Adult Cardiovascular Disease Risk

“…This impairment in myocardial functional reserve was also a predictor of the widely reported lower peak maximal oxygen consumption and delayed heart rate recovery in preterm-born young adults. 23 , 24 Similarly, Goss et al 25 demonstrated using right heart catheterization that preterm-born young adults had an impaired ability to increase cardiac index and stroke volume from rest to 70% of maximum exercise capacity determined during invasive cardiopulmonary exercise testing. These studies support the idea that preterm-born young adults have impairments in both LV and RV myocardial functional reserve, which is likely to increase susceptibility to heart failure later in life, particularly with additional insults such as hypertension or myocardial infarction.…”

“…Elevated plasma levels of angiotensin I and the presence of autonomic dysfunction and impaired heart rate recovery may suggest a potential role for angiotensin or adrenergic blockade, but these have not been specifically evaluated in preterm subjects. 23 , 24 , 78 There is evidence that neonatal risk factors do appear to be modifiable. For example, exclusive human milk feeding during infancy, as compared with formula, was associated with larger LV and RV end-diastolic and stroke volumes and smaller pulmonary artery to aortic diameter ratios in adulthood.…”

The Preterm Heart-Brain Axis in Young Adulthood: The Impact of Birth History and Modifiable Risk Factors

“…An alternative, yet not mutually exclusive, hypothesis is that the cardiovascular system may play a role in these persisting structural alterations in the brain. A lower ability of the heart to increase its output with increased demand in preterm-born young adults has been shown to lead to reductions in systemic blood flow during exercise [ 45 , 46 ]. This may cause repeated acute hypoperfusion of the brain.…”