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In A Retrospective Analysis, Late Reperfusion Appeared Safe and Effective in Stroke Patients

ARTICLE IN BRIEF

In a retrospective study, 55.5 percent of patients who had had recanalization procedures more than eight hours after onset of stroke symptoms achieved a good recovery compared with 25.6 percent of patients who did not have the procedures.

SEATTLE—Performing cranial artery recanalization more than eight hours or longer after onset of stroke symptoms results in acceptable 90-day outcomes in half the patients, researchers reported here at the AAN annual meeting.

In a retrospective study, 55.5 percent of patients who had had recanalization procedures more than eight hours after onset of stroke symptoms achieved a good recovery compared with 25.6 percent of patients who did not have the procedures (p = 0.001), said Raul G. Nogueira, MD, instructor in neurology at Massachusetts General Hospital and Harvard Medical School in Boston.

Stroke experts, who were not involved with the study, commented that though the study was provocative, the findings should be interpreted with caution. James C. Grotta, MD, professor and chairman of neurology at the University of Texas Medical School at Houston, said: “The study reflects the focus of a growing segment of the stroke community that is intent on detecting and treating those few patients with delayed emergency department arrival who may benefit from intensive therapy. However, in the process, we should not lose sight of the fact that a much greater impact will occur by treating more patients earlier.”

He said the study had limitations that are found in retrospective analyses: “The comparison with a non-randomized control group is fraught with biases and inaccuracies. Thus the conclusions must be considered hypothesis-generating only, and should stimulate further prospective randomized study,” Dr. Grotta said.

STUDY PROTOCOLS

The researchers reviewed data on 208 patients who were admitted at 12 hospitals between March 1998 and April 2009. Their mean age was 64.2 years, although they ranged in age from 19-91 years; 102 of the patients were men. The median time to treatment was 12 hours after last being seen well. The range in time to treatment was eight hours to 111 hours.

Doctors were successful in recanalization of the arteries, most frequently the middle cerebral artery, in 74 percent of the cases. The intracranial hemorrhage rate was 9.6 percent — 20 of the 208 patients; overall mortality was 22.2 percent, Dr. Nogueira said.

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DR. RAUL G. NOGUEIRA: “Similar to the experience from endovascular therapy within eight hours, successful recanalization is significantly associated with higher rates of good outcomes.”

Doctors used intraarterial thrombolytics in nearly half the patients despite being treated more than eight hours after onset of symptoms. Distal debris protective devices were used in 58 percent of the cases. In a multivariate analysis, Dr. Nogueira identified age, successful revascularization, and time-to-treatment as predictors of a good outcome. Dr. Nogueira also said that 90-day mortality among patients undergoing late recanalization — as long as 111 hours after symptom-onset — was 15.9 percent compared with 35.9 percent compared with patients who were not treated with the intaarterial procedure (p = 0.003).

“Similar to the experience from endovascular therapy within eight hours, successful recanalization is significantly associated with higher rates of good outcomes,” Dr. Nogueira said.

He noted that current selection criteria for intraarterial therapies among stoke patients with occluded vessels use a strict time window of eight hours. However, he suggested that because modern neuroimaging techniques have identified individuals with large penumbral volumes present beyond this time frame, researchers sought to explore whether these individuals are appropriate candidates for recanalization therapies.

Of the 162 patients with available datasets, 77 patients or 47.5 percent of the group achieved a Modified Rankin Scale of 2 or less, indicative of a good outcome, at 90 days. A score of 2 on the scale was defined as slight disability, meaning that an individual might not be able to carry out all the activities he or she did previously but was still independent in activities of daily living.

Dr. Nogueira said that at 90 days, 100 of the 162 patients had a score of 3 or less on the Modified Rankin Scale, indicating that the person might need some help because of moderate disability, but could still walk without assistance.

PUSHING THE ENVELOPE

“This is a provocative paper,” said Anthony J. Furlan, MD, head of the section of stroke and neurological intensive care at the Cleveland Clinic. “I think it is fair to say that we are moving from a strict time window to definition of therapy to a more of a physiological definition of salvageability. This is a very exciting study.”

Dr. Furlan, professor and chairman of neurology at Case Western Reserve University in Cleveland, who moderated the session, suggested that the “common definition of mismatch that has been used — a 20 percent mismatch between diffusion and perfusion — is clearly wrong.” He said studies indicate a much greater mismatch is required to salvage patients.

“We have had too liberal a definition of a mismatch,” he commented. “On the other side of the coin, however, there clearly are patients who have 100-to 200-percent mismatches in this time frame that — right now — we would not treat. There might not be a lot of these patients but they are certainly out there.

“The purpose of this scientific session is to sort of push the envelope,” Dr. Furlan said. “But we don't want to leave the impression that every hospital should be offering greater than eight-hour thrombolytic therapy. We do want to leave the impression that there are patients out there who could possibly benefit from this therapy and the challenge is: How do we identify those patients we can help? How do we identify the patients we will harm?”

Dr. Nogueira said a prospective, randomized trial to assess the benefit of late treatment is being planned.