Does clinical-CT 'mismatch' predict early response to treatment with recombinant tissue plasminogen activator?

Background: We hypothesized that patients with clinically severe strokes but less severe early ischemic changes on brain CT (i.e., clinical-CT mismatch) may respond better to intravenous recombinant tissue plasminogen activator (i.v. rt-PA) within 3 h of symptom onset. Methods: In this secondary analysis of the CLOTBUST data, patients with middle cerebral artery occlusions on transcranial Doppler (TCD) were treated with i.v. rt-PA. Alberta Stroke Program Early CT Scores were obtained with raters blinded to the NIH Stroke Scale and TCD results. Two mismatch criteria and three criteria of response to therapy were explored. Results: Of 126 patients, 67% had a mismatch type 1 and 74% had a mismatch type 2. The presence of clinical-CT mismatch by either definition did not correlate with any of the three criteria of response to rt-PA. Recanalization was a strong determinant of response, whether or not mismatch was present. Conclusions: Mismatch between severity of neurological deficit and CT findings is common but does not predict response to rt-PA therapy given within 3 h.