Adults born preterm show impaired left ventricular function during exercise

The hearts of adults who are born prematurely don’t function as well during exercise, possibly explaining why they’re more at risk for early heart failure, according to a study published March 19 in the Journal of the American College of Cardiology.

University of Oxford researchers recruited 47 adults aged 18 to 40 who were born preterm and 54 similar-aged adults born full term. Preterm individuals were found to have greater left ventricular mass than term-born subjects and similar left ventricular ejection fraction (LVEF) at rest.

However, at increasing levels of exercise intensity, a gap in ejection fraction emerged based on results of stress echocardiograms. At 60 percent of peak exercise intensity, the premature cohort averaged a LVEF 6.7 percent lower than full-term subjects (71.9 versus 78.6 percent). The difference grew to 7.3 percent at 80 percent exercise intensity (69.8 percent versus 77.1 percent).

In addition, the researchers noted the heart’s blood-pumping capacity during exercise was likely to be increasingly lower the more prematurely a person was born.

“Preterm-born young adults had impaired LV response to physiological stress when subjected to physical exercise, which suggested a reduced myocardial functional reserve that might help explain their increased risk of early heart failure,” wrote first author Odaro J. Huckstep, MSc, and colleagues.

“It is consequential that the systolic deficits we observed manifested under moderate intensity physical exercise and were clearly evident in this cohort of healthy, normotensive, preterm-born young adults, which indicated that, apart from subsequent pathology or insult, prematurity alone confers this systolic impairment and diminished myocardial functional reserve.”

The authors pointed out that more than 10 percent of young adults worldwide are born preterm, which means a large number of people could benefit from further research into whether lifestyle and clinical interventions could improve their cardiac function.

“Most babies born prematurely will live long and active lives, and won't go on to develop heart failure as adults,” said Jeremy Pearson, PhD, the associate medical director at the British Heart Foundation. "But the results do shed light on the way our hearts develop and how this could be different if you're born prematurely. … By understanding how the heart is affected by premature birth, we may be able to better identify people at risk of heart problems so they can be treated proactively, for example, by recommending exercise training and helping them to maintain healthy blood pressure and cholesterol levels."

In a related editorial, Anna-Karin Edstedt Bonamy, MD, PhD, and Hanna Carr, BSc—both with the Karolinska Institutet in Stockholm—pointed out the study had a small sample size but was “ambitious” and impactful in its design.

“Registry studies can be hypothesis-generating, but this type of mechanistic study is key to being able to direct preventive measures to those at risk,” they wrote. “To better learn how we can start CVD prevention in the perinatal period, we need more studies that are powered to disentangle if and how different perinatal exposures are related to later cardiovascular phenotypes.”