Alan Charles Cameron, MB ChB, BSc (Hons), MRCP

Forslund T, Komen JJ, Andersen M, Wettermark B, von Euler M, Mantel-Teeuwisse AK, et al. Improved Stroke Prevention in Atrial Fibrillation After the Introduction of Non–Vitamin K Antagonist Oral Anticoagulants: The Stockholm Experience. Stroke. 2018

The article by Forslund and colleagues clearly highlights the remarkable extent to which the introduction of non-vitamin K oral anticoagulants (NOACs) has revolutionized stroke prevention for patients with atrial fibrillation (AF). Following recommendations from the European Society of Cardiology (ESC) in 2012 that NOACs should be used first line for the majority of patients with AF, the proportion of patients with AF anticoagulated in the Stockholm County increased from 51.6% in 2012 to 73.8% in 2017. This was driven by increased NOAC prescriptions from 0.4% to 34.4%, whilst the proportion of patients prescribed warfarin decreased from 51.2% to 39.3%. Of particular importance, the greatest increase in oral anticoagulation (OAC) was in elderly patients (age ³80 years) who are at greatest risk of stroke, yet clinicians may previously have been reluctant to anticoagulate due to concerns regarding frailty. There was also increased OAC in patients at highest risk of stroke who have a high bleeding risk profile, from 33.3% to 63.6% in patients with CHA2DS2-VASc score 2-4 and from 44.1% to 72.6% in patients with CHA2DS2-VASc score 5-9.  This may reflect guidance from the ESC in 2016 to no longer withhold OAC on the basis of a high bleeding risk score; instead, the focus is on reducing modifiable risk factors for bleeding and treating more patients with NOACs.

The clinical impact of increased NOAC prescriptions was assessed using Poisson regression, which demonstrate that increased NOAC prescribing accounted for 10% of the absolute reduction in ischaemic stroke incidence over the 5-year period, after adjustment for age, sex and CHA2DS2-VASc score. The incidence of major bleeding remained similar, confirming that increased NOAC use does not increase the incidence of major bleeding. One may have expected major bleeding to reduce with increased NOAC use, since a meta-analysis of the 4 major NOAC trials for stroke prevention in AF by Ruff et al. demonstrated a trend towards reduced major bleeding with NOACs. The lack of reduction in major bleeding from 2012 to 2017 may reflect increased NOAC use in patients with high bleeding risk profiles or specific NOAC drug selections.

Overall, the article highlights the remarkable increase in OAC for patients with AF following recommendations that NOACs should be used first line. Greatest improvements were seen in elderly patients at highest risk of stroke and patients at highest risk of both stroke and bleeding. The clinical impact is remarkable with increased NOAC prescriptions accounting for 10% of the reduced stroke incidence from 2012 to 2017 and no increase in major bleeding. The study, therefore, highlights the revolution in stroke prevention for patients with AF following recommendations to prescribe NOACs first line.