Patients with atrial flutter only (AFL-only) had a 40% lower risk of ischemic stroke than those with atrial fibrillation only (AFib-only), based on results from the FinACAF study published Sept. 3 in EHJ.

The nationwide retrospective cohort study included 40,986 Finnish adults with new-onset AFib/AFL and available electrocardiogram recordings: 30,261 with AFib-only, 2,409 with AFL-only and 8,316 with AFib/AFL. Their mean age was 72 years and about half were women. Median baseline CHA₂DS₂-VA scores were 3 in the AFib-only and AFib/AFL groups and 2 in the AFL-only group.

Over a median follow-up of 1.2 years, anticoagulation was started in 78% of patients, including direct oral anticoagulation in 25% of the AFib-only group, 31% of the AFL-only group and 24% of the AFib/AFL group. Catheter ablation was performed in 2%, 7% and 6% of patients, respectively.

Overall, 8% of patients experienced an ischemic stroke, with the highest crude rate in the AFib/AFL group (2.1 per 100 patient-years), followed by the AFib-only (1.9 per 100 patient-years) and AFL-only groups (1.1 per 100 patient-years).

After adjustment, the ischemic stroke incidence rate ratio was lower in the AFL-only group (0.60) and slightly higher in the AFib/AFL group (1.11), compared with the AFib-only group. The authors suggest the lower risk in AFL-only may reflect more preserved atrial function, higher left atrial appendage emptying velocities, differences in arrhythmia burden and less structural remodeling. Findings were consistent across CHA₂DS₂-VA scores and among patients without anticoagulation or catheter ablation.

The investigators, led by Hermon Eyob Fesseha, MD, write that non-anticoagulated patients with AFL-only and a CHA₂DS₂-VA score of 1 have an annual stroke risk of 0.7%, "which falls below the threshold at which anticoagulant therapy is typically considered to provide a meaningful net benefit." By contrast, non-anticoagulated AFL-only patients with a CHA₂DS₂-VA score of 2 had an annual stroke risk of 1.6%, "indicating 'moderate' stroke risk according to the [ACC/AHA] guideline on [AFib] management and supporting the potential benefit of anticoagulation in this group."  They state these findings highlight "a potential need to re-evaluate anticoagulation strategies, particularly for patients with AFL-only and a CHA₂DS₂-VA score of 1."