Embolic stroke and after-admission atrial fibrillation

Although atrial fibrillation (AF) is a leading cause of recurrent embolic stroke, secondary AF after stroke has been reported frequently. Because of the different treatment each uses, it is important to detect the exact stroke-etiology.

The aim of this study was to compare the embolic stroke in patients with known AF and after-admission AF (AAAF).

Between October 2002 and July 2009, those who were diagnosed with AF (n=354) were enrolled in our study out of a total of 2026 acute ischemic stroke (IS) patients. The embolic lesion patterns were assessed by two stroke specialists who were blinded to the clinical information.

Among 354 IS patients with AF, the number of patients with embolic stroke was 314. Patients with embolic stroke were younger and more likely to have larger left atrial (LA)/Aortic diameter ratio. Approximately 90.4% of those with known AF had embolic stroke, while <60% of patients with AAAF had embolic stroke. Nevertheless, anticoagulants were prescribed similarly in both groups at discharge. The LA/Aortic diameter ratio<1.5 was significantly related to AAAF. After adjusting for multiple co-variables, compared to the patients with known AF, patients with AAAF had reduced risk of embolic stroke (Odds ratio 0.11, 95% Confidence interval 0.03-0.36, p-value<0.001).

Compared to AAAF after stroke, known AF was associated with embolic stroke. Therefore, we suggest that stroke etiology and some novel echocardiographic indicators such as LA enlargement might be contemplated before routine using of anticoagulants in IS patients with AF.