Mechanical thrombectomy after usual care (ie, intravenous thrombolysis) is associated with better outcomes than usual care alone for acute ischemic stroke caused by large artery occlusion, according to a meta-analysis published in the Journal of the American College of Cardiology.
In this meta-analysis, Islam Y. Elgendy, MD, of the University of Florida in Gainesville, and colleagues evaluated 9 randomized trials (MR RESCUE, IMS III, MR CLEAN, ESCAPE, EXTEND-IA, SWIFT PRIME, REVASCAT, THERAPY, and THRACE) in which 2410 patients were treated for acute ischemic stroke. All patients had presented within 4.5 hours of symptom onset, received usual care, and were randomly assigned to undergo or not undergo mechanical thrombectomy. In most cases, usual care consisted of intravenous thrombolysis. The occluded vessels were mainly the internal carotid artery and the M1 and M2 segments of the middle cerebral artery.
Of the 9 studies, 7 were accessed via Medline and 2 were European Stroke Organization Conference presentations. All the trials used intravenous tPA, but MR CLEAN also allowed the administration of intravenous urokinase. Three trials required the use of retrievable stents, 2 trials encouraged their use, and 2 others allowed them. One trial (THERAPY) used an aspiration thrombectomy device, and 3 (MR RESCUE, IMS III, and MR CLEAN) allowed intra-arterial thrombolysis alone or with mechanical thrombectomy.
The meta-analysis evaluated safety and efficacy using several outcomes. The primary outcome was “good” post-stroke function at 90 days, which was measured using the modified Rankin scale (mRS), with “good” being a score of 0 (fully independent; no deficit) to 2 (slight disability). Secondary outcomes were all-cause mortality, excellent (mRS 0 to 1) and fair (mRS 0 to 3) post-stroke function, and recanalization. Safety outcomes were symptomatic intracranial hemorrhage (ICH) and recurrent stroke.
Compared with usual care alone, administered within the recommended therapeutic window, the addition of mechanical thrombectomy to usual care was associated with a 45% higher relative likelihood and a 13% higher absolute likelihood of good functional outcome; a trend toward reduced risk of all-cause mortality; higher likelihood of both excellent and fair functional outcomes 90 days post-stroke; and improved recanalization. Six of the 9 trials reported recanalization rates compared with usual care alone (66.6% vs 39.2%; relative risk [RR]: 1.57; 95% confidence interval [CI]; P=.01). In the MR RESCUE trial, the use of advanced imaging techniques before mechanical thrombectomy delayed recanalization.
The risk of in-hospital, symptomatic ICH was similar for the mechanical thrombectomy and non-thrombectomy groups (5.1% vs 5.0%; RR: 1.06; 95% CI; P=.76). The risk of recurrent stroke at 90 days was higher for the thrombectomy group, but not significantly (5.0% vs 2.8%; RR:1.97; 95% CI; P=.24); this finding reflected the higher rate of embolic stroke in the MR CLEAN trial, where recurrent stroke was defined differently, and where some patients in the mechanical thrombectomy group underwent a simultaneous acute cervical carotid stenting.
The authors concluded that mechanical thrombectomy after usual care was associated with “improved functional outcomes,” compared with usual care alone, in acute ischemic stroke due to large artery occlusion. They also noted that the procedure, though “relatively safe,” is presently performed at specialized centers of excellence. While intravenous thrombolysis is still the “cornerstone” of treatment, <30% of eligible stroke patients receive it within the recommended timeframe.
“Future studies may need to explore the benefit of contemporary mechanical thrombectomy alone among patients who are not pre-treated with intravenous thrombolysis,” the researchers concluded.
Elgendy IY, Kumbhani DJ, Mahmoud A, Bhatt DL, Bavry, AA. Mechanical thrombectomy for acute ischemic stroke: a meta-analysis of randomized trials. Journal of the American College of Cardiology. 2015;66(22):2498-2505. http://dx.doi.org/10.1016/j.jacc.2015.09.070.