Sex Difference in Effectiveness of Early Rhythm- over Rate-Control in Patients with Atrial Fibrillation.

Background: This study aimed to investigate the associations between sex and the relative effect of rhythm control over rate control in patients with atrial fibrillation. Methods: We used the National Health Insurance Service database to select patients treated for atrial fibrillation within one year after diagnosis. The primary composite outcome comprised cardiovascular death, ischemic stroke, heart failure hospitalization, or acute myocardial infarction. Results: During the mean follow-up (4.9 ± 3.2 years), the benefit of rhythm control over rate control on the primary composite outcome became statistically insignificant after 3 months from atrial fibrillation diagnosis in women while remained steadily until 12 months in men. The risk of primary composite outcome for rhythm control was lower than that for rate control in both sexes if it was initiated within 6 months (men: HR = 0.86, 95%CI = 0.79-0.94; women: HR = 0.85, 95%CI = 0.78-0.93; P for interaction = 0.844). However, there was significant interaction between sex and the relative effect of rhythm control if it was initiated after 6 months (men: HR = 0.72, 95%CI = 0.52-0.99; women: HR = 1.32, 95%CI = 0.92-1.88; P for interaction = 0.018). Conclusion: Rhythm control resulted in lower risk of primary composite outcome than rate control in both sexes; however, the treatment initiation at an earlier stage might be considered in women.