Comparison of Mechanical Embolectomy and Intraarterial Thrombolysis in Acute Ischemic Stroke within the MCA: MERCI and Multi MERCI compared to PROACT II

Intraarterial thrombolysis and mechanical embolectomy have been studied for endovascular treatment of stroke. The MERCI and Multi MERCI trials of mechanical embolectomy with or without adjuvant intraarterial thrombolysis demonstrated effective recanalization, but with a higher mortality compared with control patients in the PROACT II trial of intraarterial thrombolysis. Differences in trial design may account for this mortality difference. We identified patients in the MERCI and Multi MERCI trials who would have been eligible for PROACT II. Rates of good outcome (mRS a parts per thousand currency sign2) and mortality at 90 days were compared, adjusting for differences in baseline NIHSS score and age. Sixty-eight patients enrolled in MERCI and 81 enrolled in Multi MERCI were eligible for PROACT II. In both unadjusted and adjusted analyses, PROACT II-eligible embolectomy patients showed a trend toward better clinical outcomes compared to the PROACT II control arm (adjusted, MERCI 35.4% [p = ns], Multi MERCI 42.8% [p = 0.048], PROACT II control, 25.4%). In both unadjusted and adjusted analyses, mortality rates did not significantly differ between embolectomy patients and PROACT II control patients (adjusted analysis, MERCI 29.1%, Multi MERCI 18.0%, PROACT II control, 27.1%). Compared with the PROACT II treatment group, embolectomy groups showed similar rates of good outcome and mortality. Differences in mortality and proportion of good outcome between the MERCI/Multi MERCI trials and the PROACT II trial are explained by differences in study design and baseline characteristics of patients. Mechanical embolectomy and IA thrombolysis may each be reasonable strategies for acute stroke; a randomized trial is necessary to confirm these results.