Endovascular therapy for acute ischemic stroke was safe even for M2 occlusions of the middle cerebral artery, a retrospective study suggested.
Ninety days after stroke therapy, good outcomes — per the modified Rankin Scale — were more likely for patients who underwent stent retriever or aspiration procedures (62.8% versus 35.4% for medical management, OR 3.1, 95% CI 2.1-4.4). Endovascular therapy came out on top even after multivariable adjustment (OR 3.2, 95% CI 2-5.2).
Even so, rates of symptomatic intracerebral hemorrhage were similar between groups (5.6% for thrombectomy versus 2.1% for medical management, P=0.10), according to Amrou Sarraj, MD, of University of Texas at Houston Stroke Center, and colleagues.
The best outcomes with thrombectomy were observed for younger patients and fast reperfusion cases, as well as those with lower stroke severity scores or smaller baseline infarcts, they wrote in JAMA Neurology.
“Although a randomized clinical trial is needed to confirm these findings, available data suggest that endovascular therapy is reasonable, safe, and effective for large vessel occlusion of the M2 segment relative to best medical management,” the investigators concluded, adding that their data were in line with results of recent endovascular therapy trials.
“With a rate of successful reperfusion of 78%, which is higher than what was achieved on average in the trials [published in 2015], the study also shows that mechanical thrombectomy is technically feasible for M2 occlusions,” added Jonathan M. Coutinho, MD, PhD, of the Netherlands’ Academic Medical Centre in Amsterdam.
“Given its more distal location and smaller diameter, mechanical thrombectomy of M2 branches is technically more challenging and may convey a higher risk for complications. Distal occlusions also tend to respond better than proximal occlusions to intravenous thrombolysis,” he wrote in an accompanying editorial.
“The data clearly suggest that it is at least reasonable to consider mechanical thrombectomy in these patients. Whether this consideration applies to all M2 occlusions remains to be seen,” Coutinho stated, given the variety of occlusions that are encountered within this group.
The retrospective study by Sarraj’s group included 522 patients who received either endovascular therapy (n=288) or best medical management (n=234). Operators performed the procedures at 10 U.S. stroke centers. Groups were balanced except that the medical management arm was older (median age 73 versus 68, P=0.003); more likely to get IV tissue plasminogen activator treatment (74.4% versus 59.7%, P=0.001); and arrived at the emergency department sooner after symptom onset (median 86 versus 158 minutes, P=0.001).
Patients presented with high median NIH Stroke Scale scores (16 for endovascular versus 15 for medical management, P=0.90), with the authors calling overall stroke severity “comparable” to that of recent studies.
“The most important limitation of the study is that we do not know what made the physicians decide whether to treat a patient medically or with endovascular therapy,” according to Coutinho, citing variables such as age, comorbidity, and anatomic features that may have confounded the non-randomized data.
The investigators agreed that they did not report the frequency of CT or MRI scanning that might have guided treatment. Furthermore, their use of a defined M2 segment did not preclude the possibility that operators misclassified sites of occlusion.
“Although the authors report their definition in the methods, it remains uncertain whether all readers consistently used this definition,” Coutino said. “Sarraj et al defined M2 branches as vertical branches in the medial part of the sylvian fissure, which is the definition described by Fischer in 1938. Another frequently used definition is to regard all post-bifurcation branches as M2 segments regardless of the point of bifurcation.”
“Most likely, the decision to perform mechanical thrombectomy in a patient with an M2 occlusion will remain one that must be carefully weighed in each case. However, that decision certainly has become a little easier with the data from this study,” Coutinho stated.
Sarraj disclosed serving as the lead principal investigator for SELECT. He disclosed relevant relationships with Stryker Neurovascular.
Coutinho disclosed no relevant relationships with industry.
Sarraj A, et al “Endovascular therapy for acute ischemic stroke with occlusion of the middle cerebral artery M2 segment” JAMA Neurol 2016; DOI: 10.1001/jamaneurol.2016.2773.
Coutinho JM “Mechanical thrombectomy for stroke: how distal can we go?” JAMA Neurol 2016; DOI: 10.1001/jamaneurol.2016.3359.