Prevalence of MRI-defined recent silent ischemia and associated bleeding risk with thrombolysis

Abstract

Uncertainties about the frequency and the associated bleeding risk of recent silent ischemia (RSI), incidentally found on pretreatment MRI, in candidates for thrombolysis require clarification because exclusion from therapy is a serious consequence for patients with such MRI findings.We retrospectively analyzed the fluid-attenuated inversion recovery (FLAIR)/diffusion-weighted imaging (DWI) obtained before IV thrombolysis in 115 patients to search for MRI-defined RSI; these corresponded to well-developed FLAIR/DWI brain hyperintensities (RSI+), as distinct from the acute index ischemia, which typically lacked FLAIR changes. Patients without such findings were assigned to the RSI- group. Groups were compared for baseline characteristics and for rates of symptomatic and asymptomatic hemorrhagic transformation (HT) using odds ratios (OR) and their 95%confidence intervals (CI).We observed RSI in 21 patients (18.3%). The mean (SD) volume of RSI was 6.5 (12) mL (interquartile range 0.6-9). None of the baseline parameters differed between groups. There was no significant difference in rates of any type of HT between groups. Parenchymal hemorrhage type 1 or type 2 according to European Cooperative Acute Stroke Study criteria occurred in 2 (10%) RSI+ patients and in 10 (11%) RSI- patients (OR 0.88; 95% CI 0.18-4.37). Symptomatic HT, defined according to National Institute of Neurological Disorders and Stroke criteria, occurred in 1 (5%) RSI+ patient and in 10 (11%) RSI- patients (OR 0.42; 95% CI 0.05-3.47).We found that 18.3% of patients with acute stroke treated by IV thrombolysis in a stroke unit had RSI on pretreatment MRI. However, the presence of RSI was not associated with an increased risk of asymptomatic or symptomatic HT.