Atrial Function Improves Stroke Prediction in Patients with Atrial fibrillation

Yaacoub Chahine, MD – Internal Medicine Resident, University of Washington; patrick Boyle, PHD – Assistant Professor, University of Washington; Juan Carlos Del Alamo, PHD – Professor, University of Washington; Nazem Akoum, MD – Section head of Cardiac Electrophysiology, University of Washington

Purpose: Stroke contributes to significant morbidity and mortality in atrial fibrillation (AF). Clinical risk scores lack predictive accuracy and mechanistic links to thrombo-embolization. We aimed to assess the association between measures of atrial function, including left atrial emptying fraction (LAEF) and long axis strain (LAS) and stroke or TIA in AF patients (pts).

Material and Methods: Pts were identified from the University of Washington Cardiac Arrhythmia Data Repository (CADRe). Pts with prior AF ablation were excluded from the study. LA function was assessed using LAS and LAEF using cardiac magnetic resonance imaging (CMR). Semi-automated contouring of the LA wall was done through image processing software (CVI42®). (Panel A)

Results: 417 pts (average age 66±13years; 64% males) were included. The average CHA2DVASc (stroke component removed) score was 2.1±1.4. LAEF was 46.18%±11.64%, and LA LAS was 24.28%±13.45%. Univariate analysis revealed a significant association between stroke/TIA and LAEF (OR= 0.962, p= 0.024); but not with LAS (OR=0.962, p=0.091) or CHA2DVASc (OR=1.084; p=0.553). LAEF remained significantly associated with stroke in multivariate analysis, adjusting for age, gender, congestive heart failure, hypertension, coronary artery disease, and diabetes, (OR= 0.963, p= 0.042). Three other models including composite CHA2DVASc with and without LAEF with their respective ROC curves and AUC are shown in Panel B. Adding LAEF improved the AUC of CHA2DVASc (AUC 0.564 vs 0.653; p=0.048) or its components (AUC 0.539 vs 0.632; p=0.043). Using a cut off LAEF of 46.53% resulted in reclassification of 47(11.3%) pts to a higher risk category and none (0%) to lower risk.

Conclusions: Left atrial emptying fraction is independently associated with stroke or TIA, and improves the predictive accuracy of clinical risk scores in AF pts.