Novel tool for predicting residual stroke risk in atrial fibrillation: mCARS

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background Recently, CARS was proposed to predict 1-year absolute stroke risk in non-anticoagulated patients with atrial fibrillation (AF). We aimed to determine whether a modified CARS (mCARS) may be used to assess the residual stroke risk in anticoagulated AF patients. Methods We studied patient-level data of anticoagulated AF patients from the real-world Murcia AF Project and AMADEUS clinical trial. Individual mCARS was estimated for each patient using an estimated 64% risk reduction with anticoagulation. Results 3,503 patients were included (2,205 [62.9%] clinical trial and 1,298 [37.1%] real-world). In the clinical trial cohort, the median age was 71 (IQR 65-77) and CHA2DS2-VASc score 3 (IQR 2-4). In the real-world cohort, the median age was 76 (IQR 70-81) and CHA2DS2-VASc score 4 (IQR 3-5). At 1-year, there were 40 and 31 stroke events in the clinical trial and real-world cohorts, respectively. Average predicted residual stroke risk by mCARS was identical to actual stroke risk (1.8 [±1.8%] vs. 1.8% [95% CI, 1.3-2.4]) in the clinical trial, and broadly similar in the real-world (2.1 [±1.9%] vs. 2.4% [95% CI, 1.6-3.4]). Additionally, these values were comparable across the subgroups stratified by CHA2DS2-VASc score in both cohorts. AUCs of mCARS for prediction of stroke events in the clinical trial and real-world were 0.678 (95% CI, 0.598-0.758) and 0.712 (95% CI, 0.618-0.805), respectively. In an exploratory analysis, we found that mCARS was able to refine stroke risk estimation for each point of the CHA2DS2-VASc score in both cohorts. Conclusion Personalised residual 1-year absolute stroke risk in anticoagulated AF patients may be estimated using mCARS. Such patients with high residual stroke risk may benefit from more aggressive interventions and follow-up. Absolute 1-year stroke risk Clinical Trial Real-World Median (IQR) Range Median (IQR) Range CHA2DS2-VASc score 0 NA 0.9 (0.6 - 1.3) 0.2 - 1.4 CHA2DS2-VASc score 1 1.1 (0.7 - 1.4) 0.2 - 2.0 1.4 (0.9 - 1.7) 0.2 - 13.0 CHA2DS2-VASc score 2 2.0 (1.5 - 2.4) 0.3 - 10.8 2.1 (1.5 - 2.6) 0.3 - 10.8 CHA2DS2-VASc score 3 2.6 (2.1 - 3.4) 0.4 - 13.3 2.8 (2.5 - 3.4) 0.9 - 13.3 CHA2DS2-VASc score 4 3.6 (2.8 - 5.6) 0.3 - 18.1 3.9 (3.3 - 5.0) 1.1 - 21.0 CHA2DS2-VASc score 5 6.7 (3.6 - 14.0) 1.9 - 20.9 4.8 (3.9 - 12.2) 1.2 - 21.0 CHA2DS2-VASc score 6 13.6 (5.5 - 15.8) 2.4 - 21.8 12.8 (4.8 - 16.7) 2.2 - 21.8 CHA2DS2-VASc score 7 15.7 (14.5 - 17.4) 4.5 - 21.9 15.6 (5.9 - 17.5) 4.1 - 23.5 CHA2DS2-VASc score 8 16.5 (14.0 - 18.5) 13.1 - 20.3 16.9 (15.7 - 19.5) 13.6 - 21.0 IQR, interquartile range; NA, not applicable.