Endovascular Therapy May Provide No Benefit When Combined With t-PA

“The most critical feature is to treat the patients as soon as possible when they arrive in the emergency department, perhaps within 90 minutes. That’s the best chance for recovery,” said Dr. Silver in an interview. “We are nowhere near what’s being done in cardiology, where there are door-to-balloon times of an hour. We need to do that in stroke. Since we’re dealing with an organ that’s more sensitive than the heart to ischemia, we probably need to be even faster than what’s being done in cardiology. There is definitely room for improvement in our systems, perhaps by having the endovascular team stay in the hospital. Expense will be the limitation,” he added.

The results of IMS III may not change neurologists’ clinical practice. “IMS III is by no means the final word on combined therapy,” said Thomas A. Tomsick, MD, in an interview. “In Cincinnati tomorrow, if a patient with a large NIHSS score shows up, and we’re treating him with IV t-PA at two hours from stroke onset, we’re not going to do a CT angiogram to evaluate that patient. He’s going to the cath lab for angiography to see if there’s a clot suitable for endovascular therapy,” he added. Dr. Tomsick is a Professor of Radiology at the University of Cincinnati.

Five endovascular devices were used in IMS III. As new devices were adopted in clinical practice, investigators allowed them to be used in the trial to keep it clinically relevant. But recruitment for the study was slow, because experience already had convinced many clinicians that combined therapy is better than t-PA alone. As a result, the endovascular therapies used most frequently in IMS III were not the devices most widely used in clinical practice today. Major new randomized trials that compare combined therapy using state-of-the-art, more effective stent clot retriever devices to IV t-PA alone are now under way, added Dr. Tomsick.

The Future of Endovascular Therapy
The use of randomization in ongoing and future stroke trials, rather than the treatment of eligible patients with endovascular therapy outside any trial, and minimization of the time to treatment will be essential for assessing the potential benefit of endovascular therapy for acute ischemic stroke,” noted Dr. Broderick in the New England Journal of Medicine.

No matter how future trials of combined therapy turn out, endovascular therapy is not going away because some patients are not eligible to receive t-PA, Dr. Broderick observed. “Roughly 5% of patients who undergo coronary artery bypass surgery have a stroke. If you have somebody with a big stroke two days after having his or her chest cracked, you can’t use t-PA. In that case, those endovascular devices are the way we can get up in there and get rid of the clot,” he explained.

The clinical implications of IMS III are that endovascular therapy remains unproven and IV t-PA should remain the first-line treatment for patients with acute ischemic stroke within 4.5 hours after stroke onset, said Marc I. Chimowitz, MD, in an editorial published online in the February 8

Although new clinical trials of more effective IV clot busters, such as tenecteplase, and next-generation endovascular devices are urgently needed to improve stroke outcomes, patient recruitment is likely to remain a challenge. This obstacle could be overcome if Medicare placed a moratorium on reimbursement for endovascular therapy of acute ischemic stroke, except as part of a randomized trial, according to Dr. Chimowitz, who is a Professor of Neurology at the Medical University of South Carolina in Charleston.