Early reperfusion and clinical outcomes in patients with M2 occlusion: pooled analysis of the PROACT II, IMS, and IMS II studies

Abstract

A solitAry occlusion at the M 2 segment of the middle cerebral artery (MCA) is identified as the cause of stroke in 9%-38% of patients in large thrombolysis series, thus accounting for 16%-41% of all MCA infarctions in this population. [1][2][3]5,8,9,11,13,[15][16][17][18] Unfortunately, the benefit of aggressive intraarterial (IA) intervention for M 2 occlusions remains unclear and the benefit-risk ratio is debatable. Compared with the M 1 segment of the MCA and the internal carotid artery (ICA), M 2 divisions are more distal vessels with smaller calibers and thinner walls. Thus, endovascular access can be more challenging and risky. Moreover, the involved vascular territory and ischemic penumbra are more limited in size, which inevitably translates into a narrower margin of benefit. In fact, reported recanalization rates in the literature have been highly variable, ranging from 43% to 82% 1,8,12,16,17 following IA therapy and from 31% to 68% following intravenous (IV) thrombolysis. Methods. Patients with a solitary M 2 occlusion were identified from the Prolyse in Acute Cerebral Thromboembolism (PROACT) II, Interventional Management of Stroke (IMS), and IMS II trial databases and were divided into 2 groups: successful reperfusion (thrombolysis in cerebral infarction [TICI] 2-3) at 2 hours and failed reperfusion (TICI 0-1) at 2 hours. Baseline characteristics and clinical outcomes were compared.Results. Sixty-three patients, 40 from PROACT II and 23 from IMS and IMS II, were identified. Successful early angiographic reperfusion (TICI 2-3) was observed in 31 patients (49.2%). No statistically significant difference in the rates of intracerebral hemorrhage (60.9% vs 47.6%, p = 0.55) or mortality (19.4% vs 15.6%, p = 0.75) was observed. However, there was a trend toward higher incidence of symptomatic hemorrhage in the TICI 2-3 group (17.4% vs 0%, p = 0.11). There was also a trend toward higher baseline glucose levels in this group (151.5 mg/dl vs 129.6 mg/ dl, p = 0.09). Despite these differences, the rate of functional independence (modified Rankin Scale Score 0-2) at 3 months was similar (TICI 2-3, 58.1% vs TICI 0-1, 53.1%; p = 0.80).Conclusions. A positive correlation between successful early reperfusion and clinical outcome could not be demonstrated for patients with M 2 occlusion. Irrespective of reperfusion status, such patients have better outcomes than those with more proximal occlusions, with more than 50% achieving functional independence at 3 months. (http://thejns.org/doi/abs/10.3171/2014.7.JNS131430) keY woRDS • acute ischemic stroke • intraarterial thrombolysis • middle cerebral artery • outcome • reperfusion • vascular disordersAbbreviations used in this paper: IA = intraarterial; ICA = internal carotid artery; ICH = intracerebral hemorrhage; IMS = Interventional Management of Stroke; IV = intravenous; MCA = middle cerebral artery; mRS = modified Rankin Scale; NIHSS = National Institutes of Health Stroke Scale; NINDS = National Institute of Neurological Disorders and Stroke; PROACT = Prolyse in...

Alberta Stroke Program Early CT Score Infarct Location Predicts Outcome Following M2 Occlusion

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Mechanical Thrombectomy for Isolated M2 Occlusions: A Post Hoc Analysis of the STAR, SWIFT, and SWIFT PRIME Studies

“…A post hoc analysis of the Prolyse in Acute Cerebral Thromboembolism (PROACT) II, Interventional Management of Stroke (IMS), and IMS II studies found successful reperfusion in approximately half of all patients with an M2 occlusion. 10 Shi et al 11 studied 28 patients with an M2 occlusion who were enrolled in the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) and multi-MERCI trials. They found that compared with patients with an M1 occlusion, the number of required passes with the thrombectomy device was lower in those with an M2 occlusion, similar to our data.…”

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