Cardiogenic Stroke Despite Low CHA₂ DS₂ -VASc Score: Assessing Stroke risk by Left Atrial Appendage Anatomy (ASK LAA)

Introduction: In patients with atrial fibrillation (AF), LAA morphology has been suggested to modify thromboembolic event (TE) risk. We tested the hypothesis that TE in low-risk patients is associated with LAA characteristics.

Methods: Of 2,069 patients who underwent AF ablation, 25 (1.2%) had a prior TE and a low CHA₂ DS₂ -VASc score (≤1). Those patients were matched for the CHA₂ DS₂ -VASc criteria with 75 event-free patients and CT data were compared. LAA measurements, morphology (Cactus, Chicken-Wing, Windsock, Cauliflower), and takeoff of the superior and inferior edge in relation (higher or lower) to the respective takeoff of the adjacent pulmonary vein (PV) were determined. LAA flow in relation to heart rate was also compared.

Results: Univariate analysis showed that TE patients had a higher incidence of superior LAA takeoff (i.e., higher than the left superior PV; 28% vs. 4%, P = 0.002) and a higher incidence of hyperlipidemia (40% vs. 17%, P = 0.028), while LAA morphologies, inferior takeoff, and other LAA characteristics were similar between groups. Logistic regression revealed that a superior LAA takeoff (OR: 9.1, 95% CI: 2.1-38.6, P = 0.003) was the only independent predictor of TE. There was a negative correlation between heart rate and LAA flow (r = -0.2 cm/s pro bpm, P = 0.048), that was even more pronounced for the superior LAA takeoff (r = -0.67 cm/s pro bpm, P = 0.035).

Conclusion: A higher LAA takeoff is associated with a tachycardia-mediated thrombogenic flow and an increased thromboembolic risk. These findings may have implications for anticoagulation management of AF patients with low CHA₂ DS₂ -VASc scores and higher LAA takeoff.