麻豆传媒

Infants born prematurely had smaller cardiac structure persisting into adolescence and adulthood compared with those born at full term, according to a cross-sectional cohort study.

Compared to those born at term, adolescents and young adults born preterm had significantly smaller biventricular cardiac chamber size and decreased cardiac mass, reported Kara Goss, MD, of the University of Wisconsin in Madison, and colleagues. The researchers reported their findings in .

Both adolescents and adults born preterm had smaller average LV end-diastolic volume (72 vs 80 and 80 vs 92 mL/m², respectively) and LV end-systolic volume (30 vs 34 and 32 vs 38 mL/m², respectively).

The group also noted that adolescents and adults in the preterm group had a decreased cardiac mass (39.6 vs 44.4 and 40.7 vs 49.8, respectively).

Goss told 麻豆传媒 that, because cardiac structure develops through the ninth month in utero, postnatal heart growth apparently does not catch up fully in those born 2-3 months early.

But whether the reduced size is of clinical importance is less clear.

Asked for his perspective, Jay Mehta, MD, PhD, of the University of Arkansas for Medical Sciences in Little Rock, said that the smaller cardiac structure observed in this study is consistent with previous research. Although this research had a small number of study participants, he added that "even in a small number of patients, you can show cardiac abnormality."

Mehta added, however, that findings on decreased cardiac mass are new.

"One can speculate that low mass means relatively less flow to the heart," Mehta, who was not involved in the study, told 麻豆传媒. "But the implication of a smaller mass is not very clear." He said that he would be hesitant to draw conclusions about long-term outcomes from these results.

These findings communicate the need to recognize a difference between preterm individuals and the average patient that clinicians treat, said Goss. "In order to recognize that, the first thing you have to do is ask," she said. "If you know that this is a person that was born preterm, you really have to think about the possibility that their symptoms may be due to atypical things."

Study Details

Although preterm birth has been linked to adverse cardiovascular outcomes, such as ischemic disease or heart failure, little is known about the mechanisms that may lead to this increased risk. Through the use of cardiac MRI, Goss and colleagues aimed to evaluate cardiac structure and function in adolescents and young adults born prematurely.

Researchers recruited 20 adolescents and 38 adults from either the Newborn Lung Project, a cohort of infants born with a low birth weight in the late 1980s or early 2000s, or the general public. Age-matched participants born at full term were also enrolled. None of the participants smoked, and they did not have any cardiovascular or respiratory illnesses.

Imaging analysts blinded to birth history calculated LV and RV end-diastolic volume, end-systolic volume, stroke volume, cardiac output, and ventricular mass from a steady-state procession series. MRI scans were also used to analyze cardiac strain.

Goss and colleagues grouped data by age, and whether individuals were born preterm. In multivariable regression models, they investigated preterm birth characteristics including chronological age, gestational age, total days on assisted ventilation, and patent ductus arteriosus.

About 60% of participants in both the full-term and preterm cohorts were female. Mean ages of adolescents and adults in both groups were 13 and 26 years, respectively.

Those in the preterm cohort were shorter, and had higher systolic, diastolic, and mean systemic blood pressure. Average gestational age of preterm infants was 29 weeks, and 72% required invasive ventilation at birth.

Goss and colleagues noted that stroke volume index in the preterm cohort was reduced compared with the term group, measuring 42 vs 46 mL/m² in adolescents, and 48 vs 54 mL/m² among adults. Biventricular ejection fractions, however, were preserved. Resting heart rate and cardiac indexes were similar among term and preterm cohorts.

Although there were no statistically significant differences in biventricular strain among adolescent term and preterm groups, adults that were born preterm had higher LV longitudinal, RV longitudinal, and RV circumferential strain, suggesting a hypercontractile heart.

Gestational age and total days on assisted ventilation were significantly associated with RV mass index, and inversely associated with biventricular ejection fractions.

Goss and colleagues recognized that findings were limited by a small number of study participants. In addition, they said the cross-sectional study design cannot confirm differences in cardiac growth, and may not account for all confounders.

Comment