Intra-Arterial Thrombolysis Prompts "Lazarus" Phenomenon

Caroline Cassels

February 12, 2007

February 12, 2007 (San Francisco) — A new study shows almost 25% of patients with acute ischemic stroke experience significant and immediate improvement following intra-arterial (IA) thrombolytic therapy.

Presented here at the American Stroke Association International Stroke Conference 2007, investigators from the Ohio State University College of Medicine, in Columbus, looked at factors influencing the so-called "Lazarus phenomenon" (LP), in which ischemic stroke patients experience a decrease in National Institutes of Health Stroke Scale (NIHSS) score by at least 50% within 24 hours following treatment.

Investigators found the most significant predictors of LP were shorter time to IA thrombolytic treatment, good pial collateral formation, and reperfusion flow of greater than 50%.

"Some people experience a dramatic improvement [with IA] and some people don't, and we're trying to figure out the reasons for this. Based on these results, it is clear time is a major factor and every minute counts," the study's principal investigator, Dr. Gregory A. Christoforidis, told Medscape.

Time to Treatment Still Critical

According to the study, the average time to treatment was 208 minutes in patients showing rapid recovery vs 306 minutes in those who did not.

Even though IA thrombolytic therapy can be administered up to 6 hours — vs the standard 3-hour treatment window for IV tPA — it is still important that patients be treated as early as possible to achieve good outcomes, said Dr. Christoforidis.

In addition to time to treatment, patients who experienced immediate and significant improvement following IA thrombolytic treatment were those whose reperfusion was 50% or more and who had good pial collaterals to the ischemic territory.

Dr. Christoforidis said that while not all patients who meet these criteria are going to have good outcomes, the chances are reasonably good that they will.

"I don't want to give false hope. Just because a patient has great pial collaterals doesn't mean they're going to do well. On the other hand, if a patient has really brisk collaterals and receives treatment quickly, they have a much better chance of rapid improvement and recovery," he said.

Greatest Response Within 24 Hours

The study included 108 consecutive patients who underwent IA thrombolysis within 6 hours of symptom onset. However, patients receiving treatment for basilar artery thrombosis were treated up to 24 hours.

In addition to time to treatment, reperfusion, and good pial collateral formation, other risk factors included in the analysis were age, blood glucose levels, platelet counts, presenting systolic blood pressure, presenting NIHSS score, and site of occlusion, as well as the treating agent.

Only time to treatment and a reperfusion flow of 50% or more were significantly different between the 2 groups of patients.

According to the study, although there were some LP patients who continued to improve beyond 24 hours, the majority displayed most of their clinical improvement within the first 24 hours.

Dramatic Improvement

The dramatic improvement seen in this study, said Dr. Christoforidis, confirms the value of IA thrombolysis therapy. However, he noted, it takes a great deal of effort and coordination of a large team of health professionals working very rapidly to achieve optimal results. In addition, hesaid, it is a more invasive therapy than IV tPA and fewer centers are doing the procedure.

Dr. Christoforidis said his next research steps include looking at ways of augmenting pial collateral formation and investigating better methods of delivering IA thrombolytic therapy to improve outcomes.

"It is not enough just to embed a microcatheter inside a clot. There are different ways of manipulating the catheter so it distributes the [thrombolytic] agent more evenly, and we are investigating this," he said.

International Stroke Conference 2007: Abstract P99.


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