Background: It is unclear whether oral anticoagulants are beneficial for atrial fibrillation (AF) patients with low CHA2DS2-VASc score. Age could be important in determining the risk of thromboembolism in low risk AF patients (CHA2DS2-VASc score of 1 for male or 2 for female).
Methods: The Taiwan National Health Insurance Research Database (NHIRD) was used and 27,521 AF patients with CHA2DS2-VASc score of 1 (male) or 2 (female) not receiving anticoagulants were acquired as the study cohort, which were classified into three age groups: 20-49, 50-64, and 65-74 years. The clinical endpoint was the occurrence of ischemic thromboembolism within one year of follow up.
Results: During the follow-up of 0.94 ± 0.19 years, 385 (2.19%) male patients experienced ischemic thromboembolism, with annual rate of 2.32%. The annual risk ranged from 1.29%, 2.43% to 2.77% for male patients aged 20-49, 50-64 and 65-74 years respectively. Of the female patients, 218 (2.20%) experienced clinical event with annual rate of 2.32%. The annual risk increased from 1.87%, 2.28% to 2.64% for female patients aged 20-49, 50-64 and 65-74 years respectively. There was no difference in risk between the male patients aged 20-49 years with CHA2DS2-VASc score of 1 and overall male patients with CHA2DS2-VASc score of 0. (P = 0.631) The female patients aged 20-49 years with CHA2DS2-VASc score of 2 was associated with a higher risk of thromboembolic events than overall female patients with CHA2DS2-VASc score of 1 (HR = 1.93; P = 0.008).
Conclusions: Age is important in determining the risk of thromboembolism in AF patients with single risk factor. In male patients <50 years old with CHA2DS2-VASc score of 1, the risk of ischemic thromboembolism was low. Considering the benefits and the risk of bleeding, oral anticoagulation therapy may not be favorable in these patients.