Cardiac Electrical Alternans in Pregnancy: an Observational Study

Abstract

In pregnancy, if the woman has a cardiovascular disease, her fetus has an increased risk of inherited cardiac genetic disorders. Aim of this study was to evaluate electrocardiographic alternans (ECGA, $\mu V)$ of 23 pregnant women, comparing 12 mothers of fetuses with normal rhythm (Mum_NRF) and 11 mothers of arrhythmic fetuses (Mum_ArrF). ECGA is a noninvasive cardiac electrical risk marker able to reveal heart electrical instability. ECGA manifests in the ECG as P-wave alternans (PWA), QRS alternans (QRSA) and/or T-wave alternans (TWA). Analysis was performed by the enhanced adaptive matched filter method. ECGA distributions were expressed as: median (interquartile range). Comparisons were performed by the Wilcoxon rank-sum test. Although showing similar heart rate (Mum_NRF: 85 (19) bpm; Mum_ArrF: 90 (13) bpm), ECGA was higher in Mum_ArrF population than Mum_NRF one (PWA: 9 (7) $\mu V\ vs. 14 (14) \mu V;$ QRSA: 9 (10) $\mu V\ vs$ . 17 (16) $\mu V$, TWA: 12 (14) $\mu Vvs. 28(17) \mu V)$, but only TWA distributions were statistically different. Moreover, TWA was higher than in a female healthy population (on average $18\mu V)$in 70% of Mum_ArrF, vs. 33% of Mum_NRF. Thus, higher TWA in our Mum_ArrF seems to reflect a more unstable heart electrical condition of arrhythmic fetuses' mothers than normal-rhythm fetuses' mothers.