Two tales: hemorrhagic transformation but not parenchymal hemorrhage after thrombolysis is related to severity and duration of ischemia: MRI study of acute stroke patients treated with intravenous tissue plasminogen activator within 6 hours.

BACKGROUND AND PURPOSE Intracerebral hemorrhage represents the most feared complication of treatment with intravenous tissue plasminogen activator. We studied whether perfusion-weighted imaging and diffusion-weighted imaging has the potential to identify patients at risk of severe intracerebral hemorrhage after treatment with intravenous tissue plasminogen activator. METHODS We analyzed data of prospectively studied MRI selected acute ischemic stroke patients treated with intravenous tissue plasminogen activator within 6 hours. All patients were examined by perfusion- and diffusion-weighted imaging < or =6 hours. Perfusion- and diffusion-weighted imaging lesion volumes were calculated. Hemorrhagic transformation was assessed on follow-up CT or MRI and diagnosed as hemorrhagic transformation, parenchymal hemorrhage, or symptomatic intracerebral hemorrhage according to ECASS II criteria. RESULTS Of 152 patients, hemorrhagic transformation was seen in 60 (39.5%), parenchymal hemorrhage in 15 (9.9%), and symptomatic intracerebral hemorrhage in 4 (2.6%). Multiple logistic regression analysis identified onset to treatment time after 3 to 6 hours (P<0.001), a larger perfusion-weighted imaging lesion volume (P=0.002), and, as a tendency, a higher score on the National Institutes of Health Stroke Scale on admission (P=0.068) as independent predictors of hemorrhagic transformation. Neither MRI lesion volumes nor severity of symptoms, but rather only an older age tended to be associated with parenchymal hemorrhage (P=0.087). CONCLUSIONS Our results further support the concept of a different pathogenesis for hemorrhagic transformation and parenchymal hemorrhage. Whereas hemorrhagic transformation should be regarded as a clinically irrelevant epiphenomenon of ischemic damage and reperfusion, parenchymal hemorrhage appears to be related to biologic effects of tissue plasminogen activator and other pre-existing pathologic conditions, which deserve further investigation.