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It is not correct to treat atrial fibrillation (Afib) and atrial flutter as equivalent risk factors for ischemic stroke, a Taiwanese cohort study suggested.

From individuals included in the Taiwan National Health Insurance Research Database in 2001 to 2012 who were matched by age and sex (n=219,416), 3.1-year follow-up yielded the following event rates per 100 person-years among Afib, atrial flutter, and control cohorts:

• Ischemic stroke: 3.08 (95% CI 3.03-3.13) versus 1.45 (1.28-1.62) versus 0.97 (0.92-1.03)
• Heart failure hospitalization: 3.39 (3.34-3.44) versus 1.57 (1.39-1.74) versus 0.32 (0.29-0.35)
• All-cause mortality: 17.8 (17.7-17.9) versus 13.9 (13.4-14.4) versus 4.2 (4.1-4.4)

Notably, the same CHA₂DS₂-VASc score was associated with different outcomes among the three groups. For one, Afib patients had more ischemic strokes and heart failure hospitalizations than did the atrial flutter cohort at a CHA₂DS₂-VASc score of 1 or higher, but the incidence of all-cause mortality was significantly higher only at CHA₂DS₂-VASc 1-3, according to Mien-Cheng Chen, MD, of Kaohsiung Chang Gung Memorial Hospital in Taiwan, and colleagues reporting in a study published online in .

"According to the current guidelines and a meta-analysis, patients with atrial flutter should be treated in the same manner as patients with Afib for preventing ischemic stroke ... Our results suggest that the efficacy and safety of oral anticoagulants to reduce ischemic stroke in patients with atrial flutter with the currently recommended CHA₂DS₂-VASc score should be reevaluated."

The retrospective study included patients age 20 and older and excluded those with concomitant Afib and atrial flutter.

That just 20% to 30% of patients with nonvalvular Afib in Asia take oral anticoagulants "provided the opportunity to evaluate patients with Afib and atrial flutter who did not receive adequate stroke prevention therapy, thereby minimizing selection bias," Chen's group commented.

However, selection bias was still possible owing to the exclusion of patients who received catheter ablation or anticoagulation therapy during the observation period, the researchers acknowledged, adding that the study lacked data on the difference in ischemic stroke rates between atrial flutter patients with and without anticoagulation therapy at a CHA₂DS₂-VASc score of 4 or less.

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