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 CHA2DS2-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 CHA2DS2-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 CHA2DS2-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 CHA2DS2-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 CHA2DS2-VASc. Decision curve analyses did not show a marked improvement in clinical usefulness of the ABC-stroke score over the CHA2DS2-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 CHA2DS2-VASc score.