Differing Impact of Preterm Birth on the Right and Left Atria in Adulthood

Abstract

Background Preterm birth affects 10% of live births and is associated with an altered left ventricular and right ventricular phenotype and increased cardiovascular disease risk in young adulthood. Because left atrial (LA) and right atrial (RA) volume and function are known independent predictors of cardiovascular outcomes, we investigated whether these were altered in preterm-born young adults. Methods and Results Preterm-born (n=200) and term-born (n=266) adults aged 18 to 39 years underwent cardiovascular magnetic resonance imaging. LA and RA maximal and minimal volumes (absolute, indexed to body surface area, and as a ratio to ventricular volumes) were obtained to study atrial morphology, while LA and RA stroke volume, strain, and strain rate were used to assess atrial function. Secondary analyses consisted of between-group comparisons based on degree of prematurity. Absolute RA volumes and RA volumes indexed to right ventricular volumes were significantly smaller in preterm-born compared with term-born adults. In addition, RA reservoir and booster strain were higher in preterm-born adults, possibly indicating functional compensation for the smaller RA volumes. LA volumes indexed to left ventricular volumes were significantly greater in preterm-born adults as compared with term-born adults, although absolute LA volumes were similar between groups. LA and RA changes were observed across gestational ages in the preterm group but were greatest in those born very-to-extremely preterm. Conclusions Preterm-born adults show changes in LA and RA structure and function, which may indicate subclinical cardiovascular disease. Further research into underlying mechanisms, opportunities for interventions, and their prognostic value is warranted.

Keywords: cardiac remodeling; cardiovascular diseases; magnetic resonance imaging; preterm birth; transitional physiology.

Figure 1. Atrial strain and strain rate.

A, Graph demonstrating the 3 components of atrial strain (ie, reservoir strain, conduit strain, and booster strain) during the cardiac cycle. B, Graph demonstrating the 3 components of atrial strain rate (ie, reservoir strain rate, conduit strain rate, and booster strain rate) during the cardiac cycle.

Figure 2. Study flowchart.

BMI indicates body mass index; CMR, cardiovascular magnetic resonance; LA, left atrial; and RA, right atrial.

Figure 3. Differences in left and right atrial structure between preterm‐born and term‐born adults.

A, Preterm‐born adults (blue) showed similar LA maximal volume indexes but smaller RA maximal volume indexes compared with term‐born adults (green). B, Preterm‐born adults showed greater LA/LV volume ratios (ie, LA maximal volume to LV end‐diastolic volume ratios) but smaller RA/RV volume ratios (ie, RA maximal volume to RV end‐diastolic volume ratios). Box‐and‐whisker plots presented as mean and SD. P values represent between‐group comparisons that were adjusted for differing sex and age distributions using multivariable linear regression. LA indicates left atrial; LV, left ventricular; RA, right atrial; and RV, right ventricular.