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 CHA 2 DS 2 ‐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. CHA 2 DS 2 ‐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 CHA 2 DS 2 ‐VASc score of 1 and 1638 (24.0%) had a CHA 2 DS 2 ‐VASc ≥ 2. After adjusting for facility and patient characteristics, patients with a CHA 2 DS 2 ‐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 CHA 2 DS 2 ‐VASc of 1 over the 6‐week postpartum period. Patients with AF/AFL and CHA 2 DS 2 ‐VASc of 1 had a TIA/CVA rate of 1.4%, while those with CHA 2 DS 2 ‐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 CHA 2 DS 2 ‐VASc score and need for cardioversion or onset of hemodynamic shock. Conclusions Pregnant patients with a history of AF/AFL and a CHA 2 DS 2 ‐VASc score ≥ 2 are significantly more likely to experience an acute thromboembolic event following delivery than those with a CHA 2 DS 2 ‐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 CHA 2 DS 2 ‐VASc score. Prospective studies are needed to better understand risk for pregnant and postpartum patients with AF/AFL and to determine optimal management strategies.