LAUSR

Abstract Aims Anticoagulation therapy is indicated to prevent stroke in atrial flutter (AFL) and atrial fibrillation (AF) patients. However, the outcomes of solitary AFL patients may differ from those with AFL who develop AF during follow-up. This study aimed to investigate the differences in clinical outcomes: (i) among patients with solitary AFL, AF, and AFL developing AF thereafter and (ii) between solitary AFL patients with vs. without anticoagulation therapy. Methods and results This nationwide cohort study enrolled patients with solitary AFL, solitary AF, and AFL developing AF from a 12 years National Health Insurance Research Database in Taiwan. There were 230 367 patients without anticoagulation therapy in the solitary AF cohort, 8064 in the solitary AFL cohort, and 4495 in the AFL with AF cohort. The AFL with AF and solitary AF cohorts had higher incidences of ischaemic stroke and major bleeding than the solitary AFL cohort. Solitary AFL patients with anticoagulation therapy had a lower ischaemic stroke rate than those without (P < 0.05) at the level of a CHA2DS2-VASc score ≥3. Solitary AFL patients with anticoagulation therapy had a higher intracranial haemorrhage rate than those without (P < 0.05) at the level of a CHA2DS2-VASc score ≤3. Net clinical outcomes including ischaemic stroke, systemic embolization, and major bleeding favoured anticoagulation use in solitary AFL patients with a CHA2DS2-VASc score ≥4. Conclusion Solitary AFL patients without anticoagulation therapy had better clinical outcomes than AFL patients developing AF in this study. Anticoagulation therapy may offer the best net clinical outcome for solitary AFL patients with a CHA2DS2-VASc score ≥4.