Characterisation and Enhanced Residual Risk Stratification of Long-Term Post-Discharge Ischaemic Events After Atrial Fibrillation Catheter Ablation

Abstract Although the incidence of thromboembolic events after catheter ablation for atrial fibrillation (AF) is low, the residual risk persists. The nature of these long-term events remains poorly characterized, and optimal risk stratification is challenging. We therefore aimed to characterize the postablation ischemic events and develop an enhanced risk stratification model. This single-center historical cohort study enrolled 1,163 patients who underwent initial AF ablation. The primary endpoint was a composite of postdischarge ischemic events (ischemic stroke, transient ischemic attack, and systemic arterial thromboembolism SE). The predictability of clinically available risk scores and individual parameters, including left atrial volume index (LAVI), was assessed. The new model combining the strongest predictors was benchmarked against the risk score alone. Over a median follow-up of 5.1 (interquartile range: 3.1–7.1) years, 24 patients (2.1%) experienced an ischemic event (incidence: 0.38 per 100 person-years 95% confidence interval, 0.24–0.57). AF-related etiologies (cardioembolic stroke/SE) accounted for 42% of events. More than half of the events (54%) occurred when the patients were in sinus rhythm. CHA2DS2-VASc score and LAVI were the strongest predictors. A combined model incorporating both parameters showed numerically higher discrimination and modest improvement in reclassification (net reclassification improvement: 0.698 0.300–1.095, p < 0.001) and discrimination (integrated discrimination improvement: 0.009 0.002–0.017, p = 0.014) compared with the CHA2DS2-VASc score alone. In this long-term analysis, postablation ischemic events were infrequent and of mixed etiology, with noncardioembolic causes being common. A combined model integrating CHA2DS2-VASc and LAVI showed modest incremental value for residual risk stratification.