Long‐Term Stroke Risk Prediction in Patients With Atrial Fibrillation: Comparison of the ABC‐Stroke and CHA (2) DS (2)‐VASc Scores

BACKGROUND: The ABC‐stroke score (age, biomarkers [N‐terminal fragment B‐type natriuretic peptide, high‐sensitivity troponin], and clinical history [prior stroke/transient ischemic attack]) was proposed to predict stroke in atrial fibrillation (AF). This score was derived/validated in 2 clinical trial cohorts in which patients with AF were highly selected and carefully followed‐up. However, the median follow‐up was 1.9 years in the trial cohort; therefore, its long‐term predictive performance remains uncertain. This study aimed to compare the long‐term predictive performances of the ABC‐stroke and CHA (2) DS (2)‐VASc (cardiac failure or dysfunction, hypertension, age ≥75 [doubled], diabetes mellitus, stroke [doubled]—vascular disease, age 65 to 74 years and sex category [female]) scores in a cohort of anticoagulated patients with AF. METHODS AND RESULTS: We recruited 1125 consecutive patients with AF who were stable on vitamin K antagonists and followed‐up for a median of 6.5 years. ABC‐stroke and CHA (2) DS (2)‐VASc (cardiac failure or dysfunction, hypertension, age ≥75 [doubled], diabetes mellitus, stroke [doubled]—vascular disease, age 65 to 74 years and sex category [female]) scores were calculated and compared. Median CHA (2) DS (2)‐VASc and ABC‐stroke scores were 4 (interquartile range 3–5) and 9.1 (interquartile range 7.3–11.3), respectively. There were 114 ischemic strokes (1.55% per year) at 6.5 years. The C‐index of ABC‐stroke at 3.5 years was significantly higher than CHA (2) DS (2)‐VASc (0.663 versus 0.600, P=0.046), but both C‐indexes were nonsignificantly different at 6.5 years. Integrated discrimination improvement showed a small improvement (<2%) in sensitivity at 3.5 and 6.5 years with ABC‐stroke. For ABC‐stroke, net reclassification improvement was nonsignificantly different at 3.5 years, and showed a negative reclassification at 6.5 years compared with CHA (2) DS (2)‐VASc. Decision curve analyses did not show a marked improvement in clinical usefulness of the ABC‐stroke score over the CHA (2) DS (2)‐VASc score. CONCLUSIONS: In anticoagulated patients with AF followed‐up over a long‐term period, the novel ABC‐stroke score does not offer significantly better predictive performance compared with the CHA (2) DS (2)‐VASc score.