Stroke

Key Points:

• Study identifies, classifies infarcts in new, previously unaffected territories (INTs) using data from ESCAPE
• INTs less frequent than expected and not likely caused by treatment

Although infarcts in new territories (INTs) following endovascular treatment of acute ischemic stroke are relatively uncommon and unlikely to be caused by the intervention, they do appear to have an impact on clinical outcomes, according to an analysis of the ESCAPE trial published online November 10, 2016, ahead of print in the Stroke.  

Bijoy K. Menon, MD, of Foothills Medical Centre (Calgary, Canada), and colleagues used a new classification system to identify INTs among participants in the ESCAPE trial. “This classification takes into account variations in vascular anatomy and the location of the thrombus, using information on the preprocedure noninvasive vascular imaging, end-of-procedure angiography images, and the location of infarcts on follow-up imaging,” they explain. The INTs are classified based on size and catheter manipulation across the ostium of the arterial territory.

After evaluating imaging at baseline and 24 hours, the investigators identified 14 INTs among 308 patients, with similar rates in the endovascular therapy and control arms of the trial (5.0% vs 4.0%; P = .7). The new infarcts were more likely to be detected on follow-up MRI rather than noncontrast CT (11.7% vs 2.8%).

After adjusting for age, sex, and treatment type, the use of IV alteplase was associated with a lower likelihood of INT detection (3.0% vs 9.1%; OR, 0.32; 95% CI 0.11-0.96). No other variables were associated with INTs. 

Also after adjustment, patients with INTs were less likely to have a good clinical outcome, defined as an improvement of 1 point on the modified Rankin Scale (mRS; table 1).

Table 1. Factors Associated With 90-Day Shift in mRS

“With the success of the recent endovascular treatment trials, an issue of interest in the stroke community is the safety of the procedure itself,” write the authors. “Endovascular treatment is an invasive procedure; as such, it has been assumed that the procedure is likely to dislodge thrombi into as yet unaffected arterial territories.”

They note that an initial ESCAPE report identified 32 infarcts as INTs, a number that dropped to 14 using the new classification system. “The remaining infarcts were explainable as preprocedural or likely to be in the primary vascular territory involved,” they say. 

The authors add that the rate of INTs identified does not appear to be associated with use of endovascular therapy. But, they say, the new infarcts may be more common when IV alteplase is not used, refuting concerns that alteplase may actually increase INTs by disintegrating preexisting thrombi within the cardiac or large arterial system. 

“Our analysis also shows that no other variable of interest was associated with the occurrence of INTs,” they write. “It could therefore be hypothesized that thrombi causing INTs may occur before, with, or after the index ischemic stroke event potentially as a result of the same pathology. Intravenous alteplase is possibly therapeutic, perhaps by dissolving not just the target thrombus but also any new thrombi that may have formed or embolized during this time.” 

The authors conclude that “INTs are uncommon but affect clinical outcome and are likely an epiphenomena of the acute ischemic stroke process rather than a complication of ischemic stroke treatment, especially in experienced centers.”

Sources:

Ganesh A, Al-Ajlan FS, Sabiq F, et al. Infarct in a new territory after treatment administration in the ESCAPE randomized controlled trial (Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion with Emphasis on Minimizing CT to Recanalization Times). Stroke. 2016;Epub ahead of print.

Disclosures:

Dr. Menon reports serving on the steering and executive committee of the ESCAPE trial, which received support from Covidien; serving as site principal investigator for the SOCRATES trial (Acute Stroke or Transient Ischemic Attack Treated With Aspirin or Ticagrelor and Patient Outcomes), which was sponsored by AstraZeneca; receiving honoraria from Penumbra; holding a provisional patent for triaging systems in ischemic stroke; receiving research funding from the Canadian Institutes of Health Research (CIHR), the Heart and Stroke Foundation of Canada, Alberta Innovates Health Solutions, Hotchkiss Brain Institute, and the Faculty of Medicine of the University of Calgary; and receiving salary support from CIHR.

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