Is asymptomatic hemorrhagic transformation really innocuous?

Objectives: Asymptomatic hemorrhagic transformation (HT) is not associated with immediate deterioration of patients with acute ischemic stroke. However, it is unclear whether it is clinically innocuous with respect to long-term outcome. The aim of this study was to determine the impact of asymptomatic HT on 3-month outcome. Methods: A consecutive series of 1,618 patients, hospitalized between January 2004 and August 2007 for ischemic stroke within 7 days from symptom onset were identified in a prospective stroke registry database. Those who had no evidence of acute cerebral ischemia on diffusionweighted MRI, who did not undergo T2-weighted gradient echo MRI, whose modified Rankin Scale (mRS) score at 3 months after stroke onset was not available, or who had symptomatic HT were excluded. The odds ratio (OR) of asymptomatic HT was calculated for the full distribution of mRS score and adjusted for variables with p < 0.25 with respect to their associations with asymptomatic HT or functional outcome. Results: Of 1,412 patients eligible for the study, 100 (7.1%) had asymptomatic HT. Patients who experienced asymptomatic HT were more likely to have cardioembolic stroke, to receive thrombolytic therapy, to receive anticoagulation with heparin, and to have a higher initial NIH Stroke Scale score. The crude and adjusted ORs of asymptomatic HT for an increment of mRS score at 3 months were 2.94 (95% confidence interval 2.05-4.24) and 1.90 (1.27-2.82), respectively. Conclusions: Our study shows that the odds of a worse outcome are increased by a factor of 2 in patients with asymptomatic HT compared with those without HT after acute ischemic stroke.