Giving patients with certain acute ischemic strokes intra-arterial treatment in addition to tissue plasminogen activator led to better outcomes compared with usual care, MR CLEAN researchers reported online Dec. 17 in the New England Journal of Medicine.

The MR CLEAN (Multicenter Randomized Clinical trial of Endovascular treatment for Acute ischemic stroke in the Netherlands) trial randomized 500 patients with acute ischemic stroke from a proximal intracranial arterial occlusion who could be treated within six hours of symptom onset with intra-arterial treatment and usual care, or usual care alone. Intra-arterial treatment included thrombolysis, mechanical treatment or both, and usual care could include intravenous alteplase or urokinase treatment. Occlusions were verified by imaging.

The research team, led by O.A. Berkhemer, MD, of Erasmus Medical Center in Rotterdam, the Netherlands, enrolled patients between December 2010 and March 2014 in 16 Dutch centers. In the intervention group, 84.1 percent of patients received intra-arterial treatment, many involving retrievable stents.

Based on the modified Rankin scale at 90 days, a greater proportion of the intervention group was functionally independent (Rankin score of 0 to 2), at 32.6 percent vs. 19.1 percent for the control group. The average National Institutes of Health Stroke Scale was 2.9 points lower in the intervention group after five and seven days. Assessment by CT angiography showed that a higher proportion of the intervention group achieved an absence of residual occlusion at the target site (75.4 percent vs. 32.9 percent).

Berkhemer et al found no significant difference in mortality and the rate of adverse events, although 8.6 percent of the intervention group had embolization of new vascular territories.

The results from MR CLEAN run counter to previous trials that found no benefit with intra-arterial treatment. The MR CLEAN team noted several differences in their study design and technologies, including the availability of CT angiography and retrievable stents and a successful recruitment program; in 2013, insurance companies in the Netherlands made reimbursement contingent on participation in the trial.