Outcome after intravenous thrombolysis in embolic stroke of undetermined source compared to cardioembolic stroke.

Background: It is assumed that most cases of embolic stroke of undetermined source (ESUS) are of cardioembolic origin. The data about outcome after the treatment with intravenous thrombolysis (IVT) for this type of acute ischemic stroke (AIS) are limited. We aimed to compare clinical characteristics and outcomes after IVT for AIS between patients with ESUS and cardioembolic stroke (CS).

Methods: This study was a single center retrospective analysis of stroke patients treated with IVT. The Trial of ORG 10172 in Acute Stroke Treatment criteria were used to establish stroke etiology subtype at 3 months, while ESUS was considered a subset of stroke of undetermined etiology, defined according to 2014 international criteria. Functional outcome was assessed at 3 months and defined as excellent (modified Rankin scale 0-1) and favorable (modified Rankin scale 0-2).

Results: Total of 394 patients were treated with IVT; 113 had a cardioembolism, 88 had undetermined stroke subtype, of which 62 met the ESUS criteria. Patients with ESUS were on average younger (63.7 years versus 69.7 years, p = 0.001), had a lower National Institutes of Health Stroke Scale (NIHSS) score on admission (12 versus 15, p = 0.002) and lower prevalence of antiplatelets use (27.4% versus 42.5%, p = 0.04) compared with CS patients. Favorable outcome was more likely in ESUS patients, at discharge (48.4% versus 24.0%, p = 0.002) and after 3 months (71.0% versus 37.2%, p < 0.001). Hemorrhagic transformation was less frequent (17.7% versus 33.6%, p = 0.03) in ESUS patients. Independent predictors of 3‑month favorable outcome were ESUS, the absence of leukoaraiosis on computed tomography (CT) and absence of diabetes as a risk factor.

Conclusion: Patients with ESUS had better outcome after IVT than patients with CS, which can be attributed to younger age and milder strokes in these patients.