Preterm Birth and Cardiovascular Risks

Among all births, 5-18% of deliveries occur preterm all over the world. Apart from cerebral palsy, behavioral problems, hearing and vision impairment, preterm babies are more prone to cardiovascular and metabolic problems in adulthood.

In the latest issue of JAMA Cardiology, Afifah et al. found that preterm-born individuals have higher blood pressure with an increased risk of hypertension by young adulthood, as well as potentially adverse cardiac remodeling even when normotensive.

Individuals born preterm are at greater relative risk of early heart failure and ischemic heart disease, with risk increasing according to the degree of prematurity. Part of this risk may be attributed to altered cardiac physiology because preterm-born individuals have potentially adverse structural and functional changes across developmental stages from birth to young adulthood. This includes impaired left ventricular (LV) diastolic function, smaller internal LV dimensions, and a greater rate of LV hypertrophy from childhood to young adulthood.

A cross-sectional cohort study was conducted at the Oxford Cardiovascular Clinical Research Facility, including 468 adults aged 18 to 40 years. Of these, 200 were born preterm (<37 weeks' gestation) and 268 were born at term (≥37 weeks' gestation). Cardiac magnetic resonance imaging was used to characterize LV structure and function, with clinical blood pressure readings measured to assess hypertension status.

Key Findings of the Study

• Preterm-born individuals without hypertension had smaller LV dimensions and volumes compared with both term-born individuals with and without hypertension.
• Longitudinal peak systolic strain as well as midventricular and apical peak systolic circumferential strain measures were lower in the preterm-born normotensive group compared with term-born individuals with and without hypertension.
• The association between systolic blood pressure and LV mass index in the adjusted regression models was significant across all groups but was greatest in those born very and extremely preterm.
• There was a significant, positive association between systolic blood pressure and LV mass to end-diastolic volume ratio in the preterm-born adults but not in term-born adults.

As the premature heart transitions to ex utero life, it must undergo cellular, structural, and functional adaptations to deal with the dramatic shift in oxygen and pressure. Considering lower myocardial functional reserve and underlying morphological impairments, it is conceivable that mild blood pressure elevation may have significant cardiac remodeling in this population.

With increasing survival of extreme preterm neonates, it is noteworthy that this group needs lifelong clinical follow-up and primary prevention strategies targeting early cardiovascular disease.

Source: Mohamed A, Marciniak M, Williamson W, et al. Association of Systolic Blood Pressure Elevation With Disproportionate Left Ventricular Remodeling in Very Preterm-Born Young Adults: The Preterm Heart and Elevated Blood Pressure. JAMA Cardiol. Published online May 12, 2021. doi:10.1001/jamacardio.2021.0961