Stroke Risk and Treatment in Patients with Atrial Fibrillation and Low CHA2DS2‐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 (CHA2DS2VASc=1) (or women with CHA2DS2VASc=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 CHA2DS2VASc scores. Methods and Results We compared characteristics, treatment strategies, and outcomes among patients with a CHA2DS2VASc=0, CHA2DS2VASc=1, females with a CHA2DS2VASc=2, and CHA2DS2VASc ≥2 in ORBIT‐AF (Outcomes Registry for Better Informed Treatment of Atrial Fibrillation) I & II. Compared with CHA2DS2VASc ≥2 patients (84.2%), those with a CHA2DS2VASc=0 (60.3%), 1 (69.9%), and females with a CHA2DS2VASc 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 CHA2DS2VASc=0, 0.8 (95% confidence interval [CI] [0.5–1.2]) in those with CHA2DS2VASc=1, 0.8 (95% CI [0.4–1.6]) in females with a CHA2DS2VASc score=2, and 1.7 (95% CI [1.6–1.9]) in CHA2DS2VASc ≥2. All‐cause mortality (per 100 patient‐years) was highest in females with a CHA2DS2VASc score=2 (1.4) (95% CI [0.8–2.3]), compared with patients with a CHA2DS2VASc=0 (0.2) (95% CI [0.1–1.0]), and CHA2DS2VASc=1 (1.0) (95% CI [0.7–1.4]), but lower than patients with a CHA2DS2VASc ≥2 (5.7) (95% CI [5.4–6.0]). Conclusion The majority of CHA2DS2VASc=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 CHA2DS2VASc=0‐1 as well as among females with a CHA2DS2VASc score=2. Clinical Trial Registration URL:http://www.clinicaltrials.gov. Unique identifier: NCT01701817.