Prematurity marks the adult heart

By Eleanor McDermid, Senior medwireNews Reporter

People born preterm have compromised cardiac structure and function as young adults, a study shows.

Other recent research has shown altered arterial hemodynamics, increased blood pressure and heart rate, and an overactive sympathetic system in people and animals born preterm.

"The most obvious clinical implication of this new knowledge is that young people born very preterm need continued and tailored follow-up, taking the total cardiovascular risk factor burden into account," says Mikael Norman (Karolinska Institutet & University Hospital, Stockholm, Sweden) in an editorial accompanying the study in Circulation.

In the study, left ventricular mass measured with magnetic resonance imaging was an average of 121.1 g in 102 people aged between 23 and 28 years who were born prematurely. This was a significant 19 g higher than the 102.1 g average found in 102 people of similar age and gender distribution who were born at term. The association persisted after accounting for blood pressure.

Among the premature participants, the more preterm they were, the higher their left ventricular mass was, report Paul Leeson (John Radcliffe Hospital, Oxford, UK) and colleagues.

The team believes these changes are caused by the increased cardiac output and end-diastolic pressure associated with birth occurring before the heart is sufficiently mature.

A previous study showed that left ventricular mass increased significantly more in the month after preterm than term birth. Leeson et al say this could have simply reflected what would have occurred in utero, had the babies not been born early. "However, our data are consistent with the rapid increase in neonatal left ventricular mass being a pathological event that persists into adult life."

In addition, they found that the left ventricles of the preterm group were shorter than those of the term group, with increased ventricle wall thickness and reduced cavity diameter, and the apex was shifted away from the right ventricle.

Prematurity also impacted cardiac function, with the preterm group having reduced function on a number of measures, including end-systolic volume and stroke volume, peak systolic strain rate, and systolic basal and apical rotation rates.

Gestational age was the strongest independent predictor of cardiac structure and function, with other perinatal factors - birthweight, early postnatal weight gain, and days of ventilation - having little or no impact.

However, maternal preeclampsia had an adverse effect on longitudinal peak systolic strain, on top of the effect of prematurity.

"Approximately 10% of births are now preterm, and with the first generation of very preterm-born survivors now reaching young adulthood, our findings are of considerable public health interest," say the researchers.

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