Background and purpose: The role of early and delayed recanalization after thrombolysis in the development of hemorrhagic transformation (HT) subtypes remains uncertain. We sought to explore the association between the timing of recanalization and HT risk in patients with proximal middle cerebral artery (MCA) occlusion treated with intravenous recombinant tissue plasminogen activator (rtPA) <3 hours of stroke onset and to investigate the relationship between HT subtypes, infarct volume, and outcome.
Methods: Thirty-two patients with acute stroke caused by proximal MCA occlusion treated with rtPA <3 hours of symptom onset were prospectively studied. Serial transcranial Doppler examinations were performed on admission and at 6, 12, 24, and 48 hours. Presence and type of HT were assessed on CT at 36 to 48 hours. Modified Rankin scale was used to assess outcome at 3 months.
Results: Early and delayed recanalization was identified in 17 patients (53.1%) and 8 patients (25%), respectively. HT was detected in 14 patients (43.7%): 4 (12.5%) with hemorrhagic infarction (HI1), 5 (15.6%) with HI2, 3 (9.3%) with parenchymal hematoma (PH1), and 2 (6.8%) with PH2. Distribution of HT subtypes differed significantly (P=0.025), depending on the time to artery reopening. Eight of 9 (89%), 1 of 5 (20%), and 8 of 18 (44.4%) with HI1-HI2, with PH1-PH2, and without HT, respectively, recanalized in <6 hours. Delayed recanalization was observed in 1 patient with HI1-HI2 (11%), 4 with PH1-PH2 (80%), and 3 without HT (16.6%). Neurological improvement was significantly (P<0.001) more frequent in patients with HI1-HI2 (88%) than in those without HT (39%). Infarct volume was significantly (P<0.031) lower in patients with HI1-HI2 (51.4+/-42 cm3) than in patients with PH1-PH2 (83.8+/-48 cm3) and those without HT (98.4+/-84 cm3, P=0.021). The modified Rankin scale score was significantly lower in HI1-HI2 compared with PH1-PH2 patients (1.9+/-1.1 versus 4.6+/-1.2, P<0.001) and with those without HT (1.9+/-1.1 versus 3.5+/-2.0, P=0.009.).
Conclusions: Thrombolysis-related HI (HI1-HI2) represents a marker of early successful recanalization, which leads to a reduced infarct size and improved clinical outcome.