Abstract Body (Do not enter title and authors here): Background
Connective tissue diseases (CTDs) are systemic autoimmune disorders associated with elevated cardiovascular risk, including atrial fibrillation (AF). While catheter ablation is a common treatment for AF, data on postprocedural outcomes in patients with CTDs remain limited.

Objective
This study aimed to compare post-ablation complications between AF patients with and without CTDs, using real-world data to guide risk stratification and management.

Methods
We conducted a retrospective cohort study using the TriNetX Research Network, a federated electronic health record platform encompassing 103 healthcare organizations. Adult patients who underwent AF ablation between 2010 and 2024 were identified. Two cohorts were created: patients with CTDs (n = 7,612) and matched controls without CTDs (n = 7,612). CTDs were defined using International Classification of Diseases (ICD) codes and included conditions such as systemic lupus erythematosus, systemic sclerosis, dermatomyositis, and ankylosing spondylitis. Propensity score matching accounted for demographics, comorbidities, and medication use. Outcomes assessed over 12 months included mortality, postprocedural complications, hemorrhage, vascular complications, stroke, pulmonary embolism (PE), cardiogenic shock, esophageal perforation, repeat ablation, and myocardial infarction (MI).

Results
Patients with CTDs had higher rates of postprocedural complications (23.7% vs. 19.8%; odds ratio [OR] 1.25, 95% confidence interval [CI]: 1.16–1.35; p < 0.001), hemorrhage (0.9% vs. 0.6%; OR 1.53, 95% CI: 1.05–2.22; p = 0.025), vascular complications (1.7% vs. 1.0%; OR 1.75, 95% CI: 1.31–2.32; p < 0.001), PE (1.2% vs. 0.7%; OR 1.62, 95% CI: 1.16–2.26; p = 0.004), conduction abnormalities (11.5% vs. 9.2%; OR 1.28, 95% CI: 1.15–1.42; p < 0.001), cardioversion (8.8% vs. 7.7%; OR 1.15, 95% CI: 1.02–1.29; p = 0.020), and MI (2.9% vs. 2.1%; OR 1.41, 95% CI: 1.15–1.73; p = 0.001). No significant differences were observed in mortality (1.0% vs. 1.0%; OR 1.00, 95% CI: 0.72–1.38; p = 1), stroke (2.8% vs. 2.4%; OR 1.17, 95% CI: 0.96–1.43; p = 0.115), repeat ablation (3.7% vs. 3.2%; OR 1.17, 95% CI: 0.98–1.39; p = 0.082), or cardiogenic shock (0.2% vs. 0.2%; OR 1.00, 95% CI: 0.53–1.89; p = 1).

Conclusion
AF patients with CTDs undergoing catheter ablation experience significantly higher rates of procedural complications. These findings highlight the need for tailored risk stratification and perioperative care in this population.