Stroke Prevention in Non-valvular Atrial Fibrillation: Just Scratching the Surface?

Aims: The most dreaded complication of AF is embolic stroke. Oral anticoagulation therapy (OAC) reduces the risk of embolic stroke and associated with reduced risk of mortality in patients with non-valvular AF (NVAF) but is underused in clinical practice. The purpose of this study is to evaluate the use of OACs in Israel across the spectrum of stroke and bleeding risks, specifically in patients at elevated stroke and bleeding risk.

Methods and Results: We conducted a prospective, historical cohort study using the Clalit Health Services electronic medical records database. The study population included all Clalit members aged ≥ 25 years, with a new diagnosis of NVAF between 2008 and 2015. A total of 58,385 cases were identified. The median age was 75 years with 52.9% older than 75, 52.3% were women, 17.7% had a previous stroke and the median CHA₂DS₂-VASc score was 4. HAS-BLED score ≥3 was present in 58.9% of patients. OAC were purchased by 19,705 patients (33.8%) within the first three months of NVAF first diagnosis. The percentage of patients that purchased an OAC was 11.4% for those with no risk factors (CHA₂DS₂-VASc=0), 25% in the group with CHA₂DS₂-VASc of 1 and 37.1% for those with a CHA₂DS₂-VASc ≥2. There was a steady rise in OAC purchasing from 29% in patients between 2008-2010 to 41.4% in the last period (2014-2015). Interestingly, in patients with both a CHA₂DS₂-VASc score ≥2 and a HAS-BLED score ≥ 3, OAC purchasing increased significantly from year to year from 35.7% in 2008 to 51.1% in 2015.

Conclusions: In this real world, population-based cohort of patients with newly diagnosed AF, we found a lower than expected rate of OAC prescription. Nonetheless, we detected an encouraging increase in OAC purchasing over time especially among those at high risk for both stroke and bleeding.