In addition, an infarct in a new territory did not emerge as an independent predictor of functional outcome.
Location in the posterior circulation, but not use of IV thrombolysis, is an independent predictor of having an infarct in a new territory among patients who undergo mechanical thrombectomy for emergent large-vessel occlusion (LVO) strokes, according to a new analysis.
Occlusions in the posterior circulation were more frequent in patients with new infarcts (28% vs 10%; P < 0.001), and on multivariable analysis this stroke location emerged as the only factor independently associated with a higher likelihood of having an infarct in a new territory (OR 3.33, 95% CI 1.43-7.69).
New infarcts in previously unaffected territories, in turn, were not associated with functional outcomes, researchers led by Nitin Goyal, MD (University of Tennessee Health Science Center, Memphis), report in a paper published online recently in the Journal of NeuroInterventional Surgery.
The observation that a stroke location in the posterior circulation is associated with new infarcts “requires independent confirmation in larger, prospective, multicenter datasets,” they write.
Several randomized trials have demonstrated the benefits of mechanical thrombectomy using stent retrievers over medical therapy alone for emergent LVO stroke. At the same time, current guidelines recommend use of IV thrombolysis in mechanical thrombectomy-eligible patients in the absence of contraindications.
A recently identified complication of mechanical thrombectomy, however, is an infarct in a previously unaffected territory, defined as “an acute area of ischemia that is present in a vascular territory unrelated to the vascular distribution of the emergent LVO,” Goyal et al explain. Such events are usually identified on follow-up imaging that takes place within 24 hours of mechanical thrombectomy.
Reduction of this complication might improve functional outcomes, they say, but prior studies exploring that idea have provided conflicting results.
In this new study, the investigators evaluated 419 consecutive patients with emergent LVO strokes who were treated with mechanical thrombectomy during a 5-year period spanning 2013 to 2017. An infarct in a new territory was defined using standardized methodology proposed by the ESCAPE investigators.
Patients’ mean age was 64 years, 50% were men, and the median baseline National Institutes of Health Stroke Scale score was 16. Among them, 69% were pretreated with IV thrombolysis.
The incidence of having an infarct in a new territory was lower in patients who were treated with both mechanical thrombectomy and IV thrombolysis versus those who were treated with mechanical thrombectomy alone (10% vs 20%; P = 0.011). On multivariate analysis, however, pretreatment with IV thrombolysis was not independently related to the complication (OR 0.75; 95% CI 0.32-1.76).
The rate of 3-month functional independence, defined as a modified Rankin Scale score of 0 to 2, was lower in patients with an infarct in a new territory (30% vs 50%; P = 0.007), but a new infarct did not emerge as an independent predictor of 3-month functional independence in multivariable logistic regression models (OR 0.69, 95% CI 0.29-1.62).
The findings contradict earlier studies suggesting that pretreatment with IV thrombolysis affects the incidence of infarcts in new territories and improves functional outcomes of mechanical thrombectomy, the authors point out. This discrepancy could be related to differences in patient populations or to consideration of the status of collateral circulation, they say.
- Goyal N, Tsivgoulis G, Chang JJ, et al. Intravenous thrombolysis pretreatment and other predictors of infarct in a new previously unaffected territory (INT) in ELVO strokes treated with mechanical thrombectomy. J NeuroInterv Surg. 2019;Epub ahead of print.
- Goyal reports no relevant conflicts of interest.