Endovascular Stroke Trials Halted for Benefit

November 17, 2014

Following the positive results from MR CLEAN (Multicenter Randomized Clinical trial of Endovascular treatment for Acute ischemic stroke in the Netherlands) showing benefits of endovascular treatment in patients with stroke, two similar trials of embolectomy devices have been stopped early because of benefits in the endovascular treatment group. A third trial has been put on temporary hold for an early interim analysis.

Results of MR CLEAN, reported last month at the recent 9th World Stroke Congress, showed that endovascular intervention consisting of arterial catheterization to the site of occlusion for delivery of mechanical treatment — with most patients receiving thrombolysis first — was associated with a shift to improved function at 90 days, as reflected by a lower modified Rankin Scale score, with an adjusted odds ratio of 1.67 vs best medical therapy alone.

Since then, two other trials evaluating endovascular interventions — ESCAPE (Endovascular Treatment for Small Core and Proximal Occlusion Ischemic Stroke) and EXTEND IA (Extending the Time for Thrombolysis in Emergency Neurological Deficits - Intra-Arterial) — have been stopped after early interim analyses showed benefit in the intervention group.

In light of these preliminary reports of three positive endovascular recanalization trials, the data safety monitoring committee of the SWIFT PRIME (Solitaire FR as Primary Treatment for Acute Ischemic Stroke) study, also investigating second-generation embolectomy technology, has recommended a temporary halt in enrollment and the performance of an early interim analysis.

"The new results could have a potentially transformative effect on the treatment of stroke," global principal investigator of SWIFT PRIME, Jeffrey Saver, MD, University of California, Los Angeles, commented to Medscape Medical News. "It has long been anticipated that embolectomy would be beneficial and it is great news that we are actually seeing positive results now."

Dr Saver explained that these latest trials are mainly focusing on new second-generation embolectomy devices. The first-generation devices showed no benefit over medical therapy alone in a first round of trials in this field. These included the IMS-III (Interventional Management of Stroke III), MR RESCUE, and SYNTHESIS EXPANSON studies.

Then second-generation devices were introduced, which Dr Saver notes were shown in the SWIFT (Solitare With the Intention for Thrombectomy) and TREVO (Thrombectomy REvascularization of large Vessel Occlusions in acute ischemic stroke) trials to be more effective at opening the artery with less arterial injury and fewer hemorrhagic adverse effects than the first-generation devices.

The current trials, now reporting initial results, are mainly evaluating the second-generation devices vs best medical therapy, with clinical outcomes as the primary endpoint.

Dr Saver explained that MR CLEAN had used a pragmatic approach with various different devices included, while the EXTEND IA and SWIFT PRIME studies are testing the Solitaire device.

He pointed out that most of the studies were evaluating the new devices in combination with tissue plasminogen activator (tPA), which was given on the way to the catheterization laboratory. Patients who still had a clot on further imaging underwent endovascular treatment in the interventional arm of the studies.

However, the design of MR CLEAN involved a longer time between tPA and endovascular treatment.

Dr Saver reported that 196 patients have so far been enrolled in the SWIFT PRIME study. The study was designed with planned 833 patients, but multiple interim analyses have been built in, so early termination was always a possibility. Results from the current interim analysis are expected "very soon," he added.

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