No consistent cutoff
In participating facilities, the protocol for considering CTA to detect and treat LVOs ranges from neurologist choice to cutoffs of NIHSS scores of 2, 4, and 6, according to Dr. Sevilis. Where the data suggest that a cutoff of 4 or above might be reasonable, she said that NIHSS scoring is not a useful tool for those “who do not want to miss any LVOs.”
These data are based on emergency room stroke consultations and not on confirmed strokes,” Dr. Sevilis emphasized. Indeed, she noted that the final discharge diagnosis was not available. Recognizing that the analysis was not performed on a population with confirmed strokes is particularly important for understanding the limited rate of CTAs performed even in those with relatively high NIHSS scores. She noted this could be explained by many different reasons, including suspicion of hemorrhage or clinical features that took the workup in a different direction.
Reconsidering protocols
Based on the large sample size, Dr. Sevilis contended that it is likely that these data are representative, but she considers this study a first step toward considering protocols and developing guidelines for addressing stroke alerts in the emergency department.
A more important step will be ongoing trials designed specifically to generate data to answer this question. Pascal Jabbour, MD, chief of the division of neurovascular and endovascular neurosurgery, Thomas Jefferson University Hospitals, Philadelphia, is participating in one of these trials. He agreed with the premise that better evidence-based criteria are needed when evaluating acute stroke patients with a potential LVO.
The trial in which he is a coinvestigator, called ENDOLOW, is testing the hypothesis that outcomes will be better if acute stroke patients with a LVO and a low baseline NIHSS score (< 5) are treated with immediate thrombectomy rather than medical management. If this hypothesis is confirmed in the randomized ENDOLOW, it will provide an evidence basis for an approach already being practiced at some centers.
“There should be a very low threshold for CTA,” said Dr. Jabbour in an interview. This imaging “takes less than 2 minutes and it can provide the basis for a life-saving endovascular thrombectomy if a LVO is found.”
It is already well known that LVO is not restricted only to patients with an elevated NIHSS score, he said.
For determining whether to order a CTA, “I do not agree with NIHSS score of 6 or above. There is no absolute number below which risk of missing a LVO is eliminated,” Dr. Jabbour said. He also argued against relying on NIHSS score without considering other clinical features, particularly cortical signs, which should raise suspicion of a LVO regardless of NIHSS score.
One problem is that NIHSS scores are not static. Decompensation can be rapid with the NIHSS score quickly climbing. When this happens, the delay in treatment might lead to a preventable adverse outcome.
“There is a change in the paradigm now that we have more evidence of a benefit from aggressive treatment in the right candidates,” according to Dr. Jabbour, referring to the recently published SELECT2 trial. In that trial, on which Dr. Jabbour served as a coauthor, patients with LVO and large territory infarct were randomized to thrombectomy or medical care within 24 hours of a stroke. It was stopped early for efficacy because of the increased functional independence (20% vs. 7%) in the surgical intervention group.
If the ongoing trials establish better criteria for ruling in or out the presence of LVO in patients with acute stroke, Dr. Jabbour predicted that guidelines will be written to standardize practice.
Dr. Sevilis reports no potential conflicts of interest. Dr. Jabbour has financial relationships with Cerenovus, Medtronic, and Microvention.