Abstract Body (Do not enter title and authors here): Introduction
The incidence of arrhythmias during pregnancy and maternal mortality rates are rising. While arrhythmia risk is elevated during pregnancy and most cases are considered benign, they are known predictors of cardiac events and are the underlying cause of 10.7% of maternal cardiovascular deaths. However, there is little research on the long-term outcomes of individuals who experience arrhythmias, particularly during pregnancy.

Aims
We aimed to determine whether arrhythmias during pregnancy are associated with increased risks of adverse outcomes—stroke, cardiomyopathy, and recurrent arrhythmia—at 1, 3, and 5 years. We also analyzed outcomes by arrhythmia type.

Methods
This retrospective cohort study used data from 68 healthcare organizations in the TriNetX research network. Two main cohorts were identified: pregnancies with and without arrhythmia, each stratified by maternal age (<35 and ≥35 years). Subgroup analyses were conducted for specific arrhythmias—ventricular tachycardia (VTAC), atrial premature contractions, atrial fibrillation (AF), and supraventricular tachycardia (STAC)—each compared to matched controls. Propensity score matching (1:1) was applied using race, maternal age, type II diabetes, and obesity. Outcomes were assessed at 1, 3, and 5 years post-arrhythmia. Events with fewer than 10 cases were excluded per TriNetX de-identification policy.

Results
Patients with arrhythmia during pregnancy had significantly higher long-term risks of stroke, cardiomyopathy, and recurrent arrhythmia compared to those without. In age-stratified analysis, patients ≥35 had elevated risks for stroke (RRs: 3.24–3.94), cardiomyopathy (RRs: 4.43–5.39), and recurrence (RRs: 21.13–51.34); those <35 showed similar patterns, with even higher recurrence risk (up to RR 79.11). Although risk varied by arrhythmia type, all groups demonstrated significantly increased adverse outcomes. Stroke risk was highest in AF (RR = 5.53), and recurrence was most pronounced in STAC (RR = 75.0). Cardiomyopathy risk was elevated overall, though not significant for VTAC, and data were unavailable for AF and STAC.

Conclusion
Arrhythmias during pregnancy are strongly associated with long-term cardiovascular risk. These findings underscore the need for postpartum surveillance, individualized risk management, and further investigation into long-term outcomes.