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March 29, 2024

 

Patients with large-vessel occlusions had better 90-day functional recovery when CT perfusion indicated small ischemic core and large penumbra.

 

Patients with large-vessel-occlusion strokes who show evidence of penumbral patterns on CT perfusion have better 90-day functional outcomes than patients with nonpenumbral patterns, regardless of treatment and recanalization, according to the results of a study published online May 8, 2018, in Stroke.

“This is again evidence that physiological imaging—ie, imaging of the ischemic or penumbral pattern—will predict the optimal response to therapy,” said Kenneth Butcher, MD, PhD (University of Alberta, Edmonton, Canada), told Neurovascular Exchange. “It is time for physicians in general to stop ignoring physiological data.”

Butcher and colleagues analyzed data from the ESCAPE (Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion with Emphasis of Minimizing CT to Recanalization Times) trial. ESCAPE used CT or CT angiography to identify patients with large-vessel occlusions and small infarct cores, randomly assigning them to endovascular therapy or standard of care, including thrombolysis in eligible patients.

A penumbral pattern was defined as an infarct core < 70 mL, penumbral volume > 15 mL, and a mismatch ratio of total perfusion deficit to core volume > 1.8.

Of the 316 patients randomized in the ESCAPE trial, 138 underwent CT perfusion imaging. Penumbral patterns were identified in 90.6% of patients with interpretable images.

At 90 days, good functional outcome, defined as a modified Rankin Scale (mRS) score of 0 to 2, was observed in almost one-half (46%) of patients with a penumbral pattern, compared with only 17% with a nonpenumbral pattern (P = 0.041).

In addition, presence of a penumbral pattern was associated with better outcomes regardless of treatment and recanalization. In penumbral patients, endovascular therapy increased the likelihood of good functional outcome significantly compared with standard of care (57% vs 33%; P = 0.011).


Useful for Patient Selection

According to Butcher, use of penumbral imaging could be a better way to select patients for therapy than use of therapeutic time windows.

“This is the imaging that we think is the best way to select patients for therapy,” Butcher said. “If you don’t have penumbral pattern, even in patients who present very early, you often can’t salvage the tissue. By going through these procedures, you expose the patient to the risk of therapies, but none of the benefits.”

Similarly, there are patients who are considered to be outside of the strict treatment windows used at some institutions, but who may benefit based on the presence of the penumbral pattern, he added. 

For example, the study highlighted the results from a 59-year-old man who underwent endovascular thrombectomy that resulted in full recanalization 10.9 hours after symptom onset. The man had a penumbral pattern with minimal infarct growth and a 90-day mRS score of 2.

In contrast, another 59-year-old man who underwent endovascular thrombectomy demonstrated a nonpenumbral pattern. Despite successful endovascular treatment and recanalization 2.8 hours after symptom onset, the 24-hour infarct volume on diffusion-weighted imaging was 278.0 mL and the mRS score was 4 at day 90.

Butcher admitted that the predictive potential of penumbral pattern remains controversial.

“There are people who would tell you that most of the patients in ESCAPE who had perfusion had penumbral pattern and that, therefore, we do not need to do penumbral imaging because we selected the patients adequately using CTA and CT,” Butcher said. “Those interested in more targeted therapies would disagree. I say, there is always room for improvement.”

Butcher also acknowledged that response to endovascular therapy cannot be excluded in patients with nonpenumbral patterns, even though nonpenumbral patients were less likely to have good functional recovery in this study.

“I cannot say with 100% certainty that there are patients without penumbral pattern who present early enough that they wouldn’t benefit, but the odds decrease,” Butcher said, adding that further research is needed in such patients.

 


Sources:

Wannamaker R, Guinand T, Menon BK, et al. Computed tomographic perfusion predicts poor outcomes in a randomized trial of endovascular therapy. Stroke. 2018;Epub ahead of print.

 

Disclosures:

Butcher reports receiving salary support from Canada Research Chairs program and Heart and Stroke Foundation of Alberta, Northwest Territories and Nunavut.