Clinical Outcomes after Intravenous Fibrinolysis in Cryptogenic Strokes with or without Patent Foramen Ovale

BackgroundPivotal clinical trials suggest that intravenous (IV) recombinant tissue plasminogen activator (rt-PA) benefits stroke patients regardless of the underlying etiology. Paradoxical strokes, presumed to be caused by fibrin-rich clots originating in the venous circulation, may respond better to fibrinolysis than other ischemic stroke subtypes. In this study, we compared the response with IV rt-PA in paradoxical stroke patients and other stroke subtypes.MethodsIn total, 486 patients treated with IV rt-PA at a single institution were retrospectively reviewed. Adjudication of stroke mechanism was based on chart review. Five major stroke mechanisms—cardioembolic, artery-to-artery emboli, lacunar, cryptogenic, and paradoxical—were identified by final diagnosis from chart reviews. Mimics, undefined etiology, and defined etiology not falling into the major mechanisms were excluded. Analysis of variance and general linear model were used to assess the differences between groups.ResultsA total of 323 patients were analyzed. We found significant differences in clinical outcome between stroke mechanisms, including discharge National Institutes of Health Stroke Scale (NIHSS) (P = .007), discharge Rankin (P = .011), discharge disposition (P = .000), and infarct volume (P = .007). Post hoc analysis showed that cardioembolic patients had the worst outcomes (discharge NIHSS score 11.12 ± 12.26), whereas paradoxical strokes had the best outcomes (discharge NIHSS score 3.67 ± 4.90), but these did not approach statistical significance. However, regression analysis showed that 4 variables—congestive heart failure, admission NIHSS, age, and mean infarct volume—rather than stroke mechanism were the true predictors of poor outcome.ConclusionsParadoxical strokes had better outcomes after IV fibrinolysis than other ischemic stroke subtypes, but this difference is attributable to younger age and milder stroke severity on presentation.