Stroke Risk and Treatment in Patients with Atrial Fibrillation and Low CHA(2)DS(2)‐VASc Scores: Findings From the ORBIT‐AF I and II Registries

BACKGROUND: Current American College of Cardiology/American Heart Association guidelines suggest that for patients with atrial fibrillation who are at low risk for stroke (CHA(2)DS(2)VASc=1) (or women with CHA(2)DS(2)VASc=2) a variety of treatment strategies may be considered. However, in clinical practice, patterns of treatment in these “low‐risk” patients are not well described. The objective of this analysis is to define thromboembolic event rates and to describe treatment patterns in patients with low‐risk CHA(2)DS(2)VASc scores. METHODS AND RESULTS: We compared characteristics, treatment strategies, and outcomes among patients with a CHA(2)DS(2)VASc=0, CHA(2)DS(2)VASc=1, females with a CHA(2)DS(2)VASc=2, and CHA(2)DS(2)VASc ≥2 in ORBIT‐AF (Outcomes Registry for Better Informed Treatment of Atrial Fibrillation) I & II. Compared with CHA(2)DS(2)VASc ≥2 patients (84.2%), those with a CHA(2)DS(2)VASc=0 (60.3%), 1 (69.9%), and females with a CHA(2)DS(2)VASc score=2 (72.4%) were significantly less often treated with oral anticoagulation (P<0.0001). Stroke rates were low overall and ranged from 0 per 100 patient‐years in those with CHA(2)DS(2)VASc=0, 0.8 (95% confidence interval [CI] [0.5–1.2]) in those with CHA(2)DS(2)VASc=1, 0.8 (95% CI [0.4–1.6]) in females with a CHA(2)DS(2)VASc score=2, and 1.7 (95% CI [1.6–1.9]) in CHA(2)DS(2)VASc ≥2. All‐cause mortality (per 100 patient‐years) was highest in females with a CHA(2)DS(2)VASc score=2 (1.4) (95% CI [0.8–2.3]), compared with patients with a CHA(2)DS(2)VASc=0 (0.2) (95% CI [0.1–1.0]), and CHA(2)DS(2)VASc=1 (1.0) (95% CI [0.7–1.4]), but lower than patients with a CHA(2)DS(2)VASc ≥2 (5.7) (95% CI [5.4–6.0]). CONCLUSION: The majority of CHA(2)DS(2)VASc=0‐1 patients are treated with oral anticoagulation. In addition, the absolute risks of death and stroke/transient ischemic attack were low among both male and females CHA(2)DS(2)VASc=0‐1 as well as among females with a CHA(2)DS(2)VASc score=2. CLINICAL TRIAL REGISTRATION: URL:http://www.clinicaltrials.gov. Unique identifier: NCT01701817.