EP14.21: Longitudinal comparison of two techniques for non‐invasive measurement of cardiac output from pre‐conception to postpartum

Abstract

Several studies have compared cross-sectional non-invasive techniques for the measurement of cardiac output (CO) in pregnant women, but studies with longitudinal design are lacking. We aimed to compare the ability of two devices, Vicorder® and Innocor®, in tracking changes in CO from pre-pregnancy to post-partum in healthy women. Innocor has previously been validated against invasive techniques but not Vicorder. Non-smoking women, between 18-44 years, with BMI <35 were selected from a prospective ongoing study (CONCEIVE) on cardiovascular function from prior to pregnancy to post-partum 2014-2017. For data analysis, only healthy pregnancies were included. Measurements were obtained using Vicorder first, and then Innocor under standardised conditions, and repeated at 6 time points (non-pregnant, 6, 10, 22, and 34 weeks gestation, and post-partum). The difference in CO values obtained between time points (ΔCO) were calculated (15 ΔCO per participant for each device). We used a four-quadrant plot with exclusion zone of 0.5 L/min and calculated concordance rate, angular bias and radial limits of agreement (LOA). A concordance rate of 85% was considered acceptable. By using a linear mixed model analysis we tested whether the longitudinal change in CO differs between the two devices. 69 participants were included (1035 measurements). The concordance rate was 64%, angular bias 0.6836 and radial LOA 12.87-77.13. The longitudinal trajectory of CO recorded with the two devices differed significantly (p=0.0093). The maximum rise in CO happened in the late 1st-beginning of 2nd trimester, however with Innocor it increased by 15% compared to pre-pregnancy values and with Innocor by 7% only. Despite low angular bias, a low concordance rate suggests that the agreement between devices is poor; therefore, they shouldn't be used interchangeably within the same subject through pregnancy. Interestingly, the increase in CO from prior to pregnancy with both devices appears more modest than previously reported.