Antithrombotic Treatment May Reduce Mortality Among New-Onset Atrial Fibrillation Patients with Gray-Zone Risk of Stroke

In clinical practice, some atrial fibrillation (AF) patients were classified as having low and moderate stroke risk by the CHADS2 score (≤ 1) in 2001 but in 2012 they were not truly classified as low risk of stroke according to the CHA2DS2-VASc score (≥ 2) (defined gray zone). Therefore, a treatment gap exists in gray zone AF patients. This study aimed to evaluate whether gray zone AF patients could benefit from reduced all-cause mortality under antithrombotic treatment. This was a longitudinal cohort study performed using data from claim forms submitted to the Taiwan Bureau of National Health Insurance from January 2000 to December 2011. The new-onset AF patients consisted of a gray zone cohort with a total of 1237 patients being enrolled. The primary outcome was all-cause mortality between 2001 and 2011. Patients in the gray zone receiving antithrombotic treatment had a significant reduction in all-cause mortality [hazard ratio (HR): 0.21; 95% confidence interval (CI): 0.16-0.28] compared with the no treatment group [warfarin only: HR, 0.28 (95% CI, 0.15-0.52); warfarin + Aspirin: HR, 0.21 (95% CI, 0.15-0.30); and Aspirin only: HR, 0.22 (95% CI, 0.16-0.29) ]. All-cause mortality was notably increased when any of the following risk factors were present: age 65-74 years, age ≥ 75 years, chronic kidney disease, and vascular disease. We concluded that AF patients in the gray zone must receive either anticoagulant and/or antiplatelet treatment and there is a lower mortality in these groups during long-term follow-up. Further investigation is needed to observe whether the antithrombotic drugs have benefits for patients with AF with a CHA2DS2-VASc score < 2.