Clinical-Diffusion Mismatch and Benefit From Thrombolysis 3 to 6 Hours After Acute Stroke

Background and Purpose-The clinical-diffusion mismatch (CDM) model has been proposed as a simpler tool than perfusion-diffusion mismatch (PDM) to select acute ischemic stroke patients for thrombolytic therapy. We hypothesized that in the 3- to 6-hour time window, the effect of tPA was significantly greater in patients with CDM than in patients without CDM. Methods-This is a substudy of EPITHET, a double-blind multi-center study of 100 patients randomized to tPA or placebo 3 to 6 hours after stroke onset. MRI was obtained before treatment, and at 3 to 5 days and 90 days after treatment. Presence of PDM (perfusion deficit/DWIvolume >1.2 and perfusion deficit at least 10 mL>DWIvolume) and CDM (NIHSS >= 8 and DWIvolume <= 25 mL) was determined for each patient. We assessed lesion growth and neurological improvement (decrease in NIHSS >= 8 points between baseline and 90 days, or a 90-day NIHSS <= 1). Results-86% of the patients had PDM, but only 41% had CDM. CDM detected PDM with a sensitivity of 46% and a specificity of 86%. We found statistically significant effects of reperfusion on the rate of neurological improvement (OR 9.92, 95% CI 1.91 to 51.64; P < 0.01) and on absolute growth (difference: -59.60 mL, 95% CI -95.40 mL to -23.81 mL; P < 0.01). Neither treatment with tPA nor reperfusion had a significantly different impact on lesion growth or clinical course in CDM patients compared to patients without CDM. Conclusions-There was no increased benefit from tPA in patients with CDM. The beneficial effects of reperfusion were similar in patients with and without CDM. (Stroke. 2009; 40: 2572-2574.)