Cardiac maladaptation in obese pregnancy at term

Objectives: Obesity is an increasing problem worldwide with well-recognized detrimental effects on cardiovascular health. However, very little is known about the effect of obesity on cardiovascular adaptation to pregnancy, as existing studies are small and show conflicting results. The aim of the present study is to compare biventricular cardiac function at term in obese pregnant women and pregnant women of normal body weight utilizing conventional echocardiography indices and speckle tracking assessment.

Methods: For this prospective case control study, 40 obese, but otherwise healthy, pregnant women with a body mass index (BMI) ≥35kg/m2 and 40 healthy pregnant women with a BMI ≤30kg/m2 underwent full echocardiography at term.

Results: Obese pregnant women had significantly higher systolic blood pressure (117 vs. 109mmHg, p=0.002), cardiac output (6.73 vs. 4.89L/min, p<0.001), left ventricular mass index (74 vs. 64g/m2, p<0.001) and relative wall thickness (0.43 vs. 0.37, p<0.001). Diastolic dysfunction was present in 12.5% (n=5) of controls and 41% (n=16) of obese women (p=0.004). Left ventricular global longitudinal strain (-15.59 vs. -17.61%, p<0.001), left ventricular endocardial (-17.30 vs. -19.84±%, p<0.001) and epicardial (-13.10 vs. -15.73%, p<0.001) global longitudinal strain as well as left ventricular early diastolic strain rate (1.05 vs. 1.24s-1, p=0.006) were all significantly reduced in the obese group. No differences were observed in left ventricular twist and torsion.

Conclusion: These findings are likely to represent a maladaptive response of the heart to volume overload in pregnancy. The impact of theses changes on pregnancy outcome and long-term maternal outcome is unclear.