ABSTRACT NUMBER: ESOC2026A754 ADVANCED LEFT ATRIAL ECHOCARDIOGRAPHIC IN ATRIAL FIBRILLATION PRESENTING BREAKTHROUGH STROKE

Abstract Background and aims Patients with atrial fibrillation (AF) who experience a breakthrough ischemic stroke despite anticoagulation represent a clinically complex population. Identifying predisposing atrial characteristics may refine risk stratification. We compared left atrial characteristics across AF clinical settings, including breakthrough stroke. Methods We conducted a retrospective comparative analysis using two prospectively collected ischemic stroke cohorts and a retrospective cohort of anticoagulated AF patients without prior stroke. Three groups were compared: breakthrough AF stroke despite anticoagulation; ischemic stroke with AF diagnosed during etiologic workup (not anticoagulated at onset); and anticoagulated AF without prior stroke. Left atrial dysfunction markers were assessed, including left atrial volume index (LAVi) and strain parameters (reservoir-LASr-, contraction-LASct, conduit-LASc-). Results We analyzed 156 patients (92 breakthrough AF stroke, 34 ischemic stroke with AF not anticoagulated at stroke onset, and 30 anticoagulated AF without prior stroke), with no baseline differences. Versus AF-related ischemic stroke and anticoagulated AF patients without prior stroke, breakthrough stroke patients had higher LAVi (median [IQR], mL/m2: 51.6 [36.6–64.9] vs 38.0 [32.3–46.1], P<0.001; and 46.0 [28.1–55.7], P=0.057) and lower LASr (9.6% [6.9–16.3] vs 20.8% [14.3–30.9], P<0.001; and 18.9% [13.1–24.1], P<0.001), LASct (2.5% [0.6–7.0] vs 11.2% [5.6–15.7], P<0.001; and 8.2% [1.5–12.8], P=0.008), and LASc (7.9% [4.3–13.0] vs 10.7% [8.4–13.9], P=0.007; and 11.5% [9.4–13.8], P=0.001). Conclusions Patients with breakthrough ischemic stroke exhibit significantly impaired echocardiographic markers of left atrial dysfunction. These parameters may help identify individuals at higher risk who could benefit from closer clinical surveillance. Conflict of interest Travel support to attend scientific conferences from Daiichi Sankyo