Secondary versus primary stroke prevention in atrial fibrillation: Insights from the Darlington atrial fibrillation registry

Background and Purpose: Although atrial fibrillation (AF) patients who suffered an acute stroke are at high risk for recurrence, many patients are untreated or treated suboptimally for stroke prevention. To compare clinical outcomes of AF patients with versus without previous stroke in relation to guideline-adherent antithrombotic treatment (ATT) in a contemporary primary care population.Methods: Community cohort of 105,000 patients from 11 general practices in Darlington, England was used to assess AF stroke prevention strategies against 2014 National Institute for Health and Care Excellence (NICE) guidelines.Results: Overall, 2259 (2.15%) AF patients were identified, of which 18.9% constituted a secondary prevention cohort. For secondary prevention, ATT was guideline-adherent in 56.3%, 18.9% were over-treated and 24.8% under-treated; corresponding proportions for primary prevention were 49.5%, 11.7% and 38.8%, respectively. One-year stroke rates were 8.6% and 1.6% for secondary and primary prevention,respectively (p<0.001); corresponding all-cause mortality rates were 9.8% and 9.4%, respectively (p=0.79). On multivariable analysis, lack of ATT guideline adherence was associated with increased stroke risk for primary prevention (OR 2.95, 95% CI 1.26-6.90, p=0.013 for undertreatment); for secondary prevention, lack of guideline adherence was associated with 3increased risk of recurrent stroke (OR 2.80, 95% CI 1.25-6.27, p=0.012 for over-treatment) and all-cause death (OR 2.75, 95% CI 1.33-5.69, p=0.006 for under-treatment).Conclusions: Only approximately half of eligible AF patients are prescribed OAC in line with guidelines. Guideline-adherent ATT significantly reduces the risk of stroke amongst primary prevention patients, and both risk of recurrent stroke and death in patients with previous stroke.