Comparison of the reliability and validity of four contemporary risk stratification schemes to predict thromboembolism in non-anticoagulated patients with atrial fibrillation.

BACKGROUND: The risk of thromboembolic (TE) complications in atrial fibrillation (AF) patients is not homogeneous. Risk schemes can help target anticoagulant therapy for patients at highest risk of TE complications.

OBJECTIVES: To test the predictive ability of 4 risk schemes: The Framingham, the 8th ACCP, the ACC/AHA/ESC 2006, and the CHA₂DS₂-VASc.

METHODS: 186 patients with non-valvular AF and off anticoagulant therapy were included. All subjects who experienced a stroke, transient ischemic attack, or peripheral embolism were identified. Each schema was divided into low, intermediate, and high-risk categories. Discrimination was assessed via the c-statistic.

RESULTS: We identified 10 TE events that occurred during 668 person-years off anticoagulation therapy. All risk schemes had fair discriminating ability (c-statistic ranged from 0.59 [for CHA₂DS₂-VASc] to 0.73 [for Framingham]). The proportion of patients assigned to individual risk categories varied widely across schemes. CHA₂DS₂-VASc categorized the fewest patients into low and intermediate-risk categories, whereas the Framingham schema assigned the highest patients into low-risk strata. There were no TE events in the low and intermediate-risk categories using CHA₂DS₂-VASc, whereas the most schemes assigned patients into intermediate-risk category had a event rate ranging from 2.5 (ACC/AHA/ESC and 8th ACCP schemes) to 6% (Framingham). The negative predictive value of TE events was of 100% for the no high-risk patients using CHA₂DS₂-VASc.

CONCLUSIONS: Compared to ACC/AHA/ESC, 8th ACCP, and Framingham, CHA₂DS₂-VASc risk stratification schema may be better in discriminating between patients at a low and intermediate risk of TE complications.