Prediction of Residual Stroke Risk in Anticoagulated Patients with Atrial Fibrillation: mCARS

Our ability to evaluate residual stroke risk despite anticoagulation in atrial fibrillation (AF) is currently lacking. The Calculator of Absolute Stroke Risk (CARS) has been proposed to predict 1-year absolute stroke risk in non-anticoagulated patients. We aimed to determine whether a modified CARS (mCARS) may be used to assess the residual stroke risk in anticoagulated AF patients from 'real-world' and 'clinical trial' cohorts. We studied patient-level data of anticoagulated AF patients from the real-world Murcia AF Project and AMADEUS clinical trial. Individual mCARS were estimated for each patient. None of the patients were treated with non-vitamin K antagonist oral anticoagulants. The predicted residual stroke risk was compared to actual stroke risk. 3503 patients were included (2205 [62.9%] clinical trial and 1298 [37.1%] real-world). There was wide variation of CARS for each category of CHA₂DS₂-VASc score in both cohorts. Average predicted residual stroke risk by mCARS (1.8 ± 1.8%) was identical to actual stroke risk (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]). 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. mCARS was able to refine stroke risk estimation for each point of the CHA₂DS₂-VASc score in both cohorts. Personalised residual 1-year absolute stroke risk in anticoagulated AF patients may be estimated using mCARS, thereby allowing an assessment of the absolute risk reduction of treatment and facilitating a patient-centred approach in the management of AF. Such identification of patients with high residual stroke risk could help target more aggressive interventions and follow-up.