Characteristics and outcomes of previously known versus newly detected atrial fibrillation after ischemic stroke

Background: Newly detected atrial fibrillation after stroke (AFDAS) is a specific type of AF and have a different pathophysiology compared to patients with previously known AF before a stroke (KAF). However, the characteristics and outcomes between AFDAS and KAF have not been well studied. We aimed to further explore the clinical characteristics and long-term functional outcomes between AFDAS and KAF. Material and methods: We retrospectively analyzed acute ischemic stroke patients admitted to our hospital between 2010 and 2017, who was also diagnosed with AF. The poor outcome was defined by the combination of death and any disability as scored by the modified Rankin Scale (mRS) score. Results: Among the final sample of 698 patients, 370 (53%) were classified into KAF and 328 (47%) were AFDAS. Compared to KAF, patients with AFDAS had a lower prevalence of hypertension (P = 0.01), previous stroke (P = 0.02), higher prevalence of valvular heart disease (P = 0.02), less prescribed with anticoagulants during the hospitalization (P < 0.01), and higher mortality at 3 months (OR 1.77, 95%CI 1.07–2.92, P = 0.03). Patients with AFDAS had an increased trend of mRS score compared to KAF (3 months, OR 1.37, 95% CI 1.04–1.81, P = 0.02; 12 months, OR 1.32, 95%CI 1.01–1.75, P = 0.04). Conclusion: Patients with AFDAS had a higher risk of death and an increased trend of mRS score compared to KAF. Lower utilization of anticoagulation may be a major reason of worse outcome in AFDAS. Further investigation is required to identify whether the differences of the outcomes between AFDAS and KAF is confounded by pre-existing anticoagulation.