Chest conformation spuriously influences strain parameters of myocardial contractile function in healthy pregnant women

AIMS: Left ventricular (LV) contractility during noncomplicated pregnancy has been previously investigated by two-dimensional speckle-tracking echocardiography (2D-STE), with conflicting results. Chest abnormalities might affect myocardial strain parameters, yet this issue has not been previously investigated during pregnancy. We evaluated the influence of chest conformation on myocardial strain parameters in healthy pregnant women.

METHODS: Between October 2019 and February 2020, 50 healthy pregnant women (32.3±4.0 year/old) were consecutively studied. They underwent obstetric visit, assessment of chest shape by modified Haller index (MHI; chest transverse diameter over the distance between sternum and spine), and transthoracic echocardiography implemented with 2D-STE analysis of all myocardial strain parameters in first trimester (12–14 weeks), third trimester (36–38 weeks) and 6–9 weeks after delivery.

RESULTS: LV ejection fraction remained substantially unchanged (p=0.13), while on the average all myocardial strain parameters showed a small, but significant decrease during pregnancy, and recovered postpartum (all p<0.001). Women with concave-shaped chest wall (MHI >2.5, n=29), and those with normal chest conformation (MHI ≤2.5, n=21) were then separately analyzed. Pregnant women with MHI >2.5, but not those with MHI ≤2.5, showed a progressive but reversible decrease in all myocardial strain parameters (all p<0.001). MHI was strongly correlated with LV global longitudinal strain (r= -0.87) and LV global circumferential strain (r= -0.83) in third trimester of pregnancy.

CONCLUSIONS: Myocardial strain impairment during healthy pregnancy may not reflect intrinsic myocardial dysfunction, but rather intraventricular dyssynchrony related to a narrow antero-posterior chest diameter and raise in diaphragm, with consequent extrinsic myocardial compression.