Objective:  To evaluate the prognosis of ischemic stroke patients according to the timing of an atrial fibrillation (AF) diagnosis, we created an inception cohort of incident stroke events and compared the risk of death between stroke patients with a) sinus rhythm; b) known atrial fibrillation (KAF); and c) AF diagnosed after stroke (AFDAS). 

Methods:  We utilized the Penn AF Free study to create an inception cohort of patients with incident stroke.  Mortality events were identified after linkage with the National Death Index through June 30, 2017.  We also evaluated initiation of anticoagulants and antiplatelets across the study duration.  Cox proportional hazards models evaluated associations between stroke subtypes and death.

Results:  We identified 1,489 individuals who developed an incident ischemic stroke event:  985 did not develop AF at any point during the study period, 215 had KAF before stroke, 160 had AF detected ≤6 months after stroke and 129 had AF detected >6 months after stroke.  After a median follow-up of 4.9 [IQR 1.9, 6.8] years, 686 deaths occurred.  The annualized mortality rate was 8.8% in the stroke, no AF group; 12.2% in the KAF group, 15.8% in the AFDAS ≤6 months; and 12.7% in the AFDAS > 6 months. Patients in the AFDAS ≤6 months had the highest independent risk of all-cause mortality even after multivariable adjustment for demographics, clinical risk factors and the use of antithrombotic therapies [HR 1.62 (1.22, 2.14)].  Compared to the stroke, no AF group, those with KAF had a higher mortality risk that was rendered non-significant after adjustment.  

Conclusions: The AFDAS group had the highest risk of death, which was not explained by comorbidities or use of antithrombotic therapies.