Myocardial function and myocardial work in young adults born very preterm or with extremely low birthweight – a regional cohort study

Abstract

Background Preterm birth and low birthweight have been associated with increased risk of cardiovascular disease and heart failure at young adult age. However, clinical studies of myocardial function have reported diverging results. Echocardiographic strain analyses allow detection of subclinical early stages of cardiac dysfunction, and non-invasively estimation of myocardial work derived from left ventricular pressure-strain loops provides additional information on cardiac function. Purpose We aimed to compare systolic and diastolic myocardial function including measures of myocardial work in young adults born very preterm (<29 weeks of gestation) or with extremely low birthweight (<1000 g) (PB/ELBW) and term-born age-and gender matched controls. Methods 63 PB/ELBW and 64 controls born in Norway in the periods 1982–1985, 1991–1992, and 1999–2000 were examined with echocardiography. Left ventricular (LV) ejection fraction, LV global longitudinal strain (GLS), traditional diastolic parameters and left atrial longitudinal strain were measured. Myocardial work was estimated by the echocardiographic software from LV pressure-strain loops after determination of GLS and construction of a LV pressure curve derived from brachial cuff pressure recording and timing of mitral valve opening and closure. Results The PB/ELBW with mean age 27 years (standard deviation (SD) 6), mean birthweight 945 g (SD 217) and mean gestational age 27 weeks (SD 2) had LV systolic function mainly within normal range. Only four (<1%) had EF <50%, but 12 (19%) had borderline impaired GLS >−18% or impaired GLS >−16%. Mean GLS in PB/ELBW (−19.7% (95% confidence interval (CI): −20.4, −19.1)) was impaired compared to controls (−20.4% (95% CI: −20.9, −20.0)), p=0.01. Lower birthweight was correlated to more impaired GLS (Pearson correlation coefficient −0.2). Estimated means of EF, measures of diastolic function, left atrial reservoir strain, global constructive and wasted work, global work index and global work efficiency was similar in PB/ELBW and controls. Conclusions The young adults born preterm or with extremely low birthweight had LV systolic function mainly within normal range, but GLS was impaired compared to controls, and lower birthweight was associated with more impaired GLS. Diastolic function and global work index were similar compared to controls. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Western Norway Health Authority