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CHA2DS2VASc score is used clinically for ischemic stroke risk stratification in atrial fibrillation (AF). Some studies of patients with MI and HF have shown that the CHA2DS2VASc score can be used to stratify the risk of stroke in the absence of AF. Anticoagulation may be indicated in patients with high CHA2DS2VASc score in the absence of AF.
Method and Results
We included 1395 participants with AF who were matched to 4060 participants without AF based on age, race, and CHA2DS2-VASc score (mean age, 62 years; 57% women; 22% blacks). Participants with prevalent ischemic stroke (IS) or anticoagulant use at baseline were excluded. AF was ascertained from hospitalization discharge codes and study ECGSs. IS was physician-adjudicated. We computed (a) C-statistic to determine model discrimination of the CHA2DS2-VASc score, and (b) incidence rate difference (AF vs. no AF) for ischemic stroke. After a median follow-up of 14.7 years, 288 (5.3%) participants developed IS. The C-statistic of the CHA2DS2-VASc score for IS was not significantly different in participants with vs. without AF. The incidence rate difference of IS increases with increasing CHA2DS2-VASc score in participants with vs. without AF (Table, p for interaction between AF and CHA2DS2-VASc score <0.0001).
Absolute risk of stroke in community dwellers without AF is low even with high CHA2DS2VASc score. Therefore, this population should not receive anticoagulation therapy. AF or AF-related factor, and not only vascular risk factors, drive the risk of stroke.