Postpartum thromboembolism risk by CHA2DS2-VASc score in patients with atrial fibrillation or flutter during pregnancy.

INTRODUCTION: To evaluate whether rates of postpartum thromboembolism (TE), transient ischemic attack (TIA), and cerebrovascular accident (CVA) among patients with a history of AF/AFL differed based on CHA2DS2-VASc scores 1 versus ≥ 2 (i.e., those with risk factors beyond female sex). METHODS: This retrospective cohort study used the 2016-2021 National Readmissions Database to identify patients with a diagnosis of atrial fibrillation (AF)/atrial flutter (AFL) at delivery. The primary outcome was rate of acute thromboembolic events (TE/TIA/CVA) during delivery hospitalization or within 42 days following discharge. Secondary outcomes included cerebrovascular morbidity specifically (TIA/CVA), severe maternal morbidity (SMM), non-transfusion and cardiovascular-related SMM, mode of delivery, preterm birth, and patient disposition. CHA2DS2-VASc scores were calculated for each patient at the index hospitalization and scores compared as 1 and ≥ 2. After adjusting for facility characteristics and obesity, a modified Poisson regression model was used to estimate relationships between groups. RESULTS: The cohort consisted of 3574 delivery hospitalizations with AF/AFL, corresponding to a national estimate of 6816. Of those, 5178 (76.0%) had a CHA2DS2-VASc score of 1 and 1638 (24.0%) had a CHA2DS2-VASc ≥ 2. After adjusting for facility and patient characteristics, patients with a CHA2DS2-VASc ≥ 2 were more likely to experience an acute thromboembolic event (3.9% vs. 1.5%, aRR 2.04 [1.16, 3.60]), SMM (23.5% vs. 11.4%, aRR 1.77 [1.47, 2.14]), and pulmonary edema or acute heart failure (11.4% vs. 1.3%, aRR 7.12 [4.46, 11.01]) compared with those with CHA2DS2-VASc of 1 over the 6-week postpartum period. Patients with AF/AFL and CHA2DS2-VASc of 1 had a TIA/CVA rate of 1.4%, while those with CHA2DS2-VASc ≥ 2 had a TIA/CVA rate of 2.5%, with no statistically significant difference between groups in adjusted models (aRR 1.37 [0.74, 2.52]). No significant association was observed between CHA2DS2-VASc score and need for cardioversion or onset of hemodynamic shock. CONCLUSIONS: Pregnant patients with a history of AF/AFL and a CHA2DS2-VASc score ≥ 2 are significantly more likely to experience an acute thromboembolic event following delivery than those with a CHA2DS2-VASc of 1. Additionally, baseline rates of TIA/CVA for pregnant individuals with AF/AFL but no additional risk factors beyond sex were 1.4% during the 6-week postpartum period, suggesting that pregnancy and postpartum states have increased risk not accounted for by the CHA2DS2-VASc score. Prospective studies are needed to better understand risk for pregnant and postpartum patients with AF/AFL and to determine optimal management strategies.