"In patients with acute stroke presenting in the 6- to 24-hour time window from symptom onset, and diagnosed with a proximal arterial occlusion of the brain, those selected to clot retrieval treatment with a non-contrast head CT had similar functional and safety outcomes compared to patients selected with advanced imaging," Dr. Thanh Nguyen of Boston Medical Center and Boston University School of Medicine told Reuters Health by email.
Dr. Nguyen and her colleagues conducted the CLEAR study to compare clinical outcomes in patients selected for mechanical thrombectomy by noncontrast CT with those selected by CTP or MRI in the extended time window. They analyzed data from 1,604 consecutive patients with a median age of 70 years who presented with proximal anterior circulation occlusion stroke within six to 24 hours of time last seen well, over a seven-year period at 15 sites in five countries in Europe and North America. Patients were followed-up for 90 days from stroke onset.
As reported in JAMA Neurology, 534 patients were selected to undergo mechanical thrombectomy by CT, 752 by CTP, and 318 by MRI. After adjusting for confounders, the researchers found no difference in 90-day ordinal magnetic resonance spectroscopy (mRS) shift between patients selected by CT compared with CTP (adjusted odds ratio, 0.95; P=0.64), or CT compared with MRI (aOR, 0.95; P=0.55).
Patients selected by noncontrast CT also had similar clinical and safety outcomes as those selected by CTP or MRI.
Rates of 90-day functional independence (modified Rankin Scale scores of 0-2) were similar between patients selected by CT compared with CTP (aOR, 0.90; P=0.42), but lower in those selected by MRI than by CT (aOR, 0.79; P=0.03).
Successful reperfusion was more common in patients who underwent CT and CTP than in those who underwent MRI (88.9% and 89.5% vs. 78.9%; P<0.001). The researchers found no significant differences in symptomatic intracranial hemorrhage (CT, 8.1%; CTP, 5.8%; MRI, 4.7%; P=0.11) or 90-day mortality (CT, 23.4%; CTP, 21.1%; MRI, 19.5%; P=0.38).
Co-author Dr. Osama O. Zaidat of Bon Secours Mercy Health in Toledo, Ohio, told Reuters Health by email, "To be able to offer this very effective therapy - mechanical thrombectomy for clot removal to save lives and disability of stroke patients - using affordable and less expensive plain CT, is critical in many part of USA and worldwide where complex, expensive perfusion imaging is not readily available."
Dr. Nguyen added that her team has "received feedback from physicians from low- and middle-income countries who believe the results of this study could empower them to offer thrombectomy to patients in the extended window with a more widely available imaging technology."
She noted that the large sample size was a strength of the study, but that "limitations included its retrospective design as well as differences in imaging interpretation and selection paradigms across the centers, which could introduce bias."
Dr. Nasim Sheikh-Bahaei, an assistant professor of radiology and neuroradiology at Keck Medicine of USC in Los Angeles, who was not involved in the study, welcomed the findings.
"These results are very important for the future of stroke evaluation and treatment planning, particularly for populations in hospitals or medical centers where access to CT perfusion or MRI is limited or nonexistent," she said by email. "We can avoid potential treatment delays, reduce radiation and contrast exposure, and be more cost-effective with better utilization of resources."
Co-author Dr. Tudor G. Jovin of Cooper Medical School of Rowan University in Camden, New Jersey, said, "In most health care systems worldwide, most patients with acute stroke arrive at the hospital after 6 hours from symptoms onset, and additional imaging modalities beyond a non-contrast CT scan of the head are not available on emergent basis."
"The CLEAR study represents a lifeline for these patients," he told Reuters Health by email, "because it provides much needed evidence justifying the decision to proceed with thrombectomy even when advanced imaging cannot be performed."
SOURCE: https://bit.ly/3nEUKE4 JAMA Neurology, online November 8, 2021.
By Lorraine L. Janeczko
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