Young Adults Born Small for Gestational Age Have Reduced Exercise Capacity, Heart Structure Changes

By Marilynn Larkin

July 28, 2021

NEW YORK (Reuters Health) - Young adults born small for gestational age (SGA) had lower exercise capacity than their non-SGA peers, as well as right ventricular remodeling, in an observational study in Spain

"Taking into consideration our previous work on fetuses, children and adolescents - demonstrating clear changes in the heart's structure and function of individuals born small - we were expecting to find similar changes in adults," Dr. Fatima Crispi of Hospital Clínic and Hospital Sant Joan de Déu in Barcelona told Reuters Health by email. "However, the changes observed in the hearts of adults were not as prominent as those observed in fetuses or children, most likely due to all postnatal factors such as lifestyle and comorbidities that also impacted the heart during postnatal life."

That said, she noted, "We applied shape analysis techniques that demonstrated clear changes in the right ventricular shape, showing that it was enlarged and more curved. In addition, changes in the exercise test were very significant and clear, demonstrating a reduced exercise capacity that correlated with the cardiac shape changes, meaning that we observed functional consequences of the right ventricular remodeling."

As reported in JAMA Cardiology, Dr. Crispi and colleagues analyzed a perinatal cohort born between 1975 and 1995. Participants included 158 randomly selected young adults: 81 born SGA (birth weight below the 10th centile) or with intrauterine growth within standard reference ranges (controls).

All participants were white, with a median age at the start of the study of about 34; 53% of SGA adults were women, as were 43% of controls. All underwent cardiac magnetic resonance imaging and shape analysis, and about 80% of participants in both groups completed the exercise test.

As Dr. Crispi indicated, in the SGA group, cardiac shape analysis showed minor changes at rest in right ventricular geometry with preserved cardiac function. However, compared with controls, they also had lower exercise capacity, with decreased maximal workload (mean, 180 W vs. 214 W) and oxygen consumption (median, 26.0 mL/min/kg vs. 29.5 mL/min/kg).

Further, exercise capacity was significantly correlated with left ventricular mass.

The authors conclude, "These results support considering SGA as a risk factor that may benefit from preventive strategies. Given the high prevalence of infants born SGA, targeting lifestyle policies in this group may provide a substantial positive contribution to public health."

Dr. Crispi added, "If we identify fetal growth problems during pregnancy and we promote healthy habits from childhood, we will avoid the consequences that fetal problems can lead to in adult life."

Preventive cardiologist Dr. Lara Kovell, associate professor of medicine at UMass Medical School in Worcester, commented in an email to Reuters Health, "This study was unique in using cardiac MRIs to look at the heart structure along with cardiopulmonary exercise tests to characterize exercise capacity."

"While peak oxygen carrying capacity (VO2) was lower in those born SGA, the average was 26.0 ml/min/kg," she noted. "While it's concerning that this oxygen carrying capacity was lower than the control participants, to put this in perspective, the currently accepted indication for heart transplant is patients with peak <=12-14 ml/min/kg."

Overall, she added, "This study is like others trying to guide clinicians who care for adults born SGA. (However,) someone's history of SGA may not be something they are either aware of or discussing with their care team."

SOURCE: https://bit.ly/3i8Ed8F JAMA Cardiology, online July 21, 2021.

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