Abstract 4144108: Incorporating AI-enabled Left Atrial Volume Measurement from Coronary Artery Calcium Scans (AI-CAC) to CHA ₂ DS ₂ s-VASc Risk Score Improves Stroke Prediction in the Asymptomatic Population: The Multi-Ethnic St

Background: The CHA 2 DS 2 -VASc risk score is a clinical tool for stroke prediction. It is mainly used in patients with atrial fibrillation (AF) but is also applied to the non-AF population. We previously reported that artificial intelligence (AI)-enabled left atrial (LA) volumetry from coronary artery calcium (CAC) scans (AI-CAC) predicts AF as early as one year and outperformed CHARGE-AF and NT-proBNP. In this report, we compare AI-CAC LA volumetry to the CHA 2 DS 2 -VASc risk score and evaluate the incremental value of incorporating AI-CAC LA volume to CHA 2 DS 2 -VASc for incident stroke prediction in the non-AF population. Methods: We applied the AutoChamber TM LA volumetry component of AI-CAC to CAC scans of 5830 people without AF (52.2% women, age 61.7±10.2 years) enrolled in the Multi-Ethnic Study of Atherosclerosis (MESA) baseline (2000-2002). We used the 15-year outcomes data for incident stroke (ischemic and hemorrhagic) and assessed discrimination using the time-dependent area under the curve (AUC) between AI-CAC LA volume vs. CHA 2 DS 2 -VASc risk score. Notably, the CHA 2 DS 2 -VASc score in this non-AF population ranges from 0 to 5, whereas in the AF population it typically ranges from 0 to 9 points. Results: 252 cases of stroke accrued over 15 years. The median and mean ± SD of CHA 2 DS 2 -VASc score at baseline were 1.0 and 1.58 ± 1.15, respectively. The cumulative incidence of stroke for the 95 th percentile of AI-CAC LA volume (n=291) vs. CHA 2 DS 2 -VASc 4 or 5 points (n=364) was 13.0% and 13.7%, respectively. AI-CAC LA volume significantly improved the AUC of CHA 2 DS 2 -VASc for stroke prediction at 2-year follow-up (0.76 for CHA 2 DS 2 -VASc vs. 0.81 for CHA 2 DS 2 -VASc plus LA volume, p=0.03), 5-year follow-up (0.73 vs. 0.77, p=0.01), 10-year follow-up (0.70 vs. 0.75, p<0.0001) and 15- year follow-up (0.70 vs. 0.74, p<0.0001). Conclusion: In this multi-ethnic longitudinal cohort of people without AF, addition of LA volume significantly improved performance of the CHA 2 DS 2 -VASc risk score for stroke prediction from 2 to 15 years follow-up. Further studies are needed to evaluate the clinical utility of adding LA volume to CHA 2 DS 2 -VASc risk score in people with and without AF.