Cardiogenic Stroke Despite Low CHA2DS2-VASc Score

Abstract and Introduction

Abstract

Assessing Stroke risK by LAA 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 CHA₂DS₂-VASc score (≤1). Those patients were matched for the CHA₂DS₂-VASc criteria with 75 eventfree 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 CHA₂DS₂-VASc scores and higher LAA takeoff.

Introduction

Atrial fibrillation (AF) is one of the most common causes of cardiogenic strokes, associated with an enormous health and economic burden. AF-associated strokes are usually severe and confer an increased risk of morbidity and poor functional outcome. Validated stratification models, like CHADS₂ and CHA₂DS₂-VASc score, have helped identify individuals with high risk and guide anticoagulation therapy. However, stratification and anticoagulation of low-risk patients remain a hurdle.

The left atrial appendage (LAA) is regarded as the primary source of thrombus formation, but is not included in the above stratification models. Di Biase et al. reported 4 different LAA morphologies (Cactus, Chicken-Wing, Windsock, Cauliflower) and found that the non-Chicken-Wing morphology is associated with a 3-fold risk of prior thromboembolic event (TE). Recent data have supplemented these findings, revealed the significance of LAA orientation for TE after AF ablation and found LAA anatomy useful for TE prediction in patients with low CHADS₂ score. In clinical use, though, the CHA₂DS₂-VASc score that gives better low-risk stratification has superseded the CHADS₂ score. Therefore, the role of LAA anatomy in patients with low CHA₂DS₂-VASc scores remains to be clarified.

The main objective of the present study was to analyze the morphology and other LAA characteristics in AF patients with low CHA₂DS₂-VASc score (≤1) in order to identify their association with prior thromboembolic events, using a case–control study.