Abstract Atrial fibrillation in a cohort of patients with peripheral arterial disease. A retrospective study of a healthcare database in UK. Background There is strong evidence that peripheral arterial disease (PAD) is linked with worse outcomes in patients with atrial fibrillation (AF), which has led vascular disease to be included as one of the components of CHA2DS2-VASc score for risk stratification in AF. On the other hand, very limited evidence exists on the prognostic implication of AF in patients with PAD. Purpose The aim of this study is to identify the prevalence of AF in a cohort of PAD patients and demonstrate its association with adverse cardiovascular outcomes, limb loss and mortality. Methods This is a retrospective study of The Health Improvement Network (THIN) database, which contains computerized records from primary care physicians, covering more than 11 million patients from over 600 general practices in the UK. During the studied period from 1995 to 2017, 55540 patients with newly diagnosed PAD have been detected in the database and baseline characteristics, coexisting medical diagnoses (including AF), relevant medication and subsequent outcomes have been recorded using appropriately selected clinical codes (READ codes). A comparison of baseline characteristics was made between patients with PAD and AF and those without AF using descriptive statistics. Multivariate cox regression analysis was then performed and hazard rations for mortality, stroke or transient ischaemic attack (TIA), ischaemic heart disease (IHD), heart failure (HF) and major lower limb amputation at presence of AF were calculated, after adjustment for age, sex, ethnicity, BMI, smoking, Townsend comorbidity index, diabetes, hypertension, kidney function, and medication (lipid- lowering, antiplatelets, anticoagulants). Results From the 55540 patients with new diagnosis of PAD during the study period, 5685 (10.2%) had coexisting AF. Patients with AF were older, had higher prevalence of diabetes, hypertension and renal failure, were more likely to be on anticoagulants, antiplatelets and lipid lowering agents, were more likely to be ex-smokers but less likely to be active smokers. Mean follow up period was 5.1 (SD= 4) years. After adjustment for confounders, AF patients were at higher risk for death (HR: 1.30, 95% CI 1.24- 1.37, p<0.01) for stroke or TIA (HR: 1.46, 95% CI 1.29- 1.65, p<0.01) and for HF (HR: 1.85, 95% CI 1.65- 2.08, p<0.01). There was no significant association between AF and development of IHD (p=0.34) and limb loss (p=0.14) in this cohort. Conclusion AF is a predictor of worse prognosis in patients with PAD. Close monitoring and medical optimization of these patients is warranted. Funding Acknowledgement Type of funding source: None