Cardiac and Perinatal Outcomes Among Pregnancies with Maternal Cardiac Arrhythmias.

Background: Atrial fibrillation/flutter (AF/AFL) and supraventricular tachycardia (SVT) are common arrhythmias in pregnancy. While known to contribute to adverse outcomes, large studies have not evaluated cardiac and perinatal outcomes in individuals with these arrhythmias. Objective: To characterize the cardiac/perinatal outcomes of patients with AF/AFL and SVT in pregnancy. Methods: We performed a retrospective cohort study utilizing Epic Cosmos, a dataset from over 1,500 US hospitals. We identified pregnancies between October 25, 2021 and October 24, 2024 of patients with a diagnosis of AF/AFL and SVT using simultaneous diagnoses codes for each arrhythmia and pregnancy. A control group of pregnancies without arrhythmias was also identified. Descriptive statistics were calculated, and comparisons were made with ANOVA or Chi-square tests, as appropriate. Results: During the study period, there were 8,642 pregnant patients with AF/AFL, 29,638 with SVT, and 5,372,171 healthy pregnant controls. Patients with these arrhythmias were older (AF/AFL: 33±6, SVT: 32±6, control: 31±6, p <0.0001) with a higher BMI than the control group. Those with arrhythmias experienced higher rates of heart failure (AF/AFL: 10.8%, SVT: 3.8%, control: 0.3%), thromboembolism, stroke, preterm birth, and cesarean delivery (all p <0.0001). Patients with AF/AFL had 23.9 times higher odds of stroke compared to the control group (95% CI 21.3-27.0). Conclusions: While both AF/AFL and SVT are associated with adverse cardiac and perinatal outcomes, AF/AFL was associated with the highest risk of heart failure and stroke. Further research is needed to understand optimal perinatal AF/AFL management, especially anticoagulation therapy given the high rate of maternal stroke.