Electrocardiographic proarrhythmic changes in pregnancy of women with CHD.

OBJECTIVES: Pregnancy-related physiological adaptations result in increased heart rate as well as electrocardiographic changes such as a mean QTc prolongation of 27 ms. Pregnant women with CHD are at increased risk for cardiovascular complications. The aim of this study was to identify risk factors for abnormally prolonged QTc interval-a risk factor for ventricular arrhythmias-in pregnant women with CHD.

MATERIAL AND METHOD: Retrospective longitudinal single-centre study. Pre-pregnancy demographic and electrocardiographic risk factors for abnormal QTc duration during pregnancy of (a) > 460 ms and (b) >27 ms increase were analyzed.

RESULTS: Eighty-three pregnancies in 63 women were included, of which three had documented arrhythmias. All five Modified World Health Organization Classification of Maternal Cardiovascular Risk (mWHO) classes were represented, with 15 pregnancies (18.1%) in mWHO class I, 26 (31.3%) in mWHO II, 28 (33.7%) in mWHO II-III, 11 (13.3%) in mWHO III, and three pregnancies (3.6%) in mWHO class IV. Heart rate and QTc interval increased, while QRS duration and PR interval shortened during pregnancy. QTc duration of > 460 ms was associated with increased pre-pregnancy QTc interval, QRS duration, and weight, as well as body mass index. QTc increase of > 27 ms was associated with increased heart rate prior to pregnancy. No significant associations of electrocardiographic changes with mWHO class or CHD type were identified.

CONCLUSION: Increased QTc in pregnant women with CHD was associated with being overweight or having higher heart rate, QRS, or QTc duration prior to pregnancy. These patients should be monitored closely for arrhythmias during pregnancy.