Predicting Atrial Fibrillation Recurrence After Electrical Cardioversion

Background: Predicting atrial fibrillation (AF) recurrence after external cardioversion (ECV) is challenging. The SLAC score predicts 6-month recurrence but lacked external validation. We aimed to externally validate the SLAC score and develop an improved predictive model. Methods: We conducted a single-center retrospective study of patients who underwent successful ECV for AF between 2015 and 2020. Patients with atrial flutter, complex congenital heart disease or early AF ablation were excluded. The primary outcome was AF recurrence at 6 months. SLAC score performance was tested, and multivariable logistic regression was used to develop the SLASH score. Discrimination was assessed with the area under the curve (AUC), calibration with Hosmer-Lemeshow testing, and internal validation with bootstrapping. Results: Of 361 patients (mean age 66 ± 12 years, 61% male), 53.7% experienced AF recurrence in 6 months. Median SLAC scores were higher in recurrence patients (7 vs 2). The SLAC score demonstrated moderate discrimination (AUC 0.701), improved with a cutoff 6 (AUC 0.720). Independent predictors of recurrence included left atrial volume index 40 ml/m2, prior stroke/TIA, heart rate > 70 bpm, smoking history, and absence of post-ECV antiarrhythmic therapy. These were incorporated into the SLASH score (0-8 points), which demonstrated improved discrimination (AUC 0.781). Recurrence rates were 16.1%, 65.4%, and 78.5% in low-, moderate-, and high-risk groups, respectively, with acceptable calibration (Hosmer-Lemeshow p=0.18). Conclusion: The SLAC score provides moderate prediction of 6-month AF recurrence after ECV. The SLASH score showed superior performance and may improve risk stratification and rhythm management. Prospective validation is warranted.