News from the ASA International Stroke Conference: Endovascular Device May Divert Blood to Ischemic Areas After Stroke
ARTICLE IN BRIEF
A dual-balloon endovascular device designed to divert blood flow from the lower extremities to the brain after stroke did not significantly improve neurological outcomes in stroke patients, but did seem to deter serious disability or death.
LOS ANGELES—A dual-balloon endovascular device designed to divert blood flow from the lower extremities to the brain shows promise for treating some ischemic stroke patients, but is not quite ready for primetime, according to results of one of the first randomized trials to pit the device against standard medical management.
In the study of 515 patients, the device did not meet the primary endpoint of improving neurological function at 90 days, as measured by a composite global score that combines a score of 0 or 1 point on the 42-point National Institutes of Health Stroke Scale (NIHSS), a modified Rankin Scale (mRS) score of 0 to 1, a Barthel score of 95 to 100, and a Glasgow outcome score of 5, compared with medical management alone.
“However, this was a very high bar — almost perfect neurological function — that was almost impossible to achieve. Yes, [the device] doesn't take a patient from devastation to normal. But it can get a patient from near death to disability,” said William P. Dillon, MD, Elizabeth A. Guillaumin Professor of Radiology, and executive vice-chair and chief of neuroradiology at the University of California-San Francisco. He presented the results here at the American Stroke Association International Stroke Conference 2011.
The modified Rankin Scale is a 0-to 6-point scale, in which 0 correlates to no symptoms and 6 is death. The Barthel scale is 0- to 100- point scale in which 0 translates to not being able to perform various functions such as climbing stairs and 100 to independence. Under the Glasgow outcome scale, 0 is death and 5 is good recovery.
In the prospective Safety and Efficacy of NeuroFloTM for Treatment of Ischemic Stroke (SENTIS) trial, patients with acute ischemic stroke were randomized to the endovascular device plus standard medical management or standard medical management alone. Eligibility criteria included an NIHSS score of 8 to 15 and treatment within 14 hours of symptom onset.
According to Dr. Dillon, the NeuroFlo device is inserted through the femoral artery into the descending aorta and has independently inflatable balloons located immediately above and below the renal arteries. The balloons are sequentially inflated to produce occlusions of approximately 70 percent. The balloons are left inflated for 45 minutes and are then removed.
Olajide Williams, MD, associate professor of clinical neurology at Columbia University in New York City, called NeuroFlo “a very novel approach” for targeting ischemic stroke. The studies to date suggest we might simply be able to go around clots rather than through them, said Dr. Williams, who was not involved with the study.
Dr. Williams explained: “The theory behind it is that when you have an acute stroke, there is a period of minutes to hours when you might be able to prevent or minimize damage by diverting blood flow to an area of ischemic tissue that is not yet dead.”
“This device partially restricts blood flow in the descending aorta, diverting blood flow through retrograde flow to the cerebral collaterals, which, in turn, are capable of further increasing the delivery of oxygenated blood to the ischemic penumbra,” Dr. Williams explained.
Laboratory studies in swine demonstrated a 35 percent to 50 percent increase in cerebral blood flow with the technique, Dr. Dillon said.
In the new study, patients had a median NIHSS score of 10.0 and were treated within a median of 7.4 hours of symptom onset.
However, further analysis showed that patients who were treated with device were significantly less likely to suffer serious disability or death, as reflected a modified Rankin score of 5 or 6 at 90 days: Only 16.4 percent of patients in the treatment group were in this category versus 23.3 percent in the control group.
This translates to a significant, 30 percent lower chance of being seriously disabled or dying if treated with the device, Dr. Dillon said.
Importantly, the trial also proved that the device is safe, with no increase in major bleeds, including brain bleeds, in the treatment group, he said.
Dr. Dillon also analyzed baseline and post-treatment MR perfusion imaging scans from 26 patients who underwent NeuroFlo treatment and 29 controls.
“Results showed a signal favoring treatment in patients with a baseline mismatch of greater than 10cc plus more than 20 percent difference in mismatch on pre- and post-scans,” Dr. Dillon said.
“It seems that mismatch needs to be at least moderate for this to work, based on the idea of improved collateral flow,” he said.
“We're not going to cure stroke with this device. But there may be subsets of patients it can help,” Dr. Dillon said.
Also, the results “beg the question of whether this treatment could be used in conjunction with another procedure such as thrombolytic therapy to improve outcomes. This works immediately, as soon as you open the balloons. So you may be able to buy time,” he said, noting that “tPA [tissue plasmimogen activator] can take minutes to hours to work.”
Dr. Williams said that importantly, the device might help to increase the window for treatment from the current 4.5 hours with tPA to over 10-hours.
The study was funded by CoAxia, which makes the device. Dr. Dillon said the company is discussing whether to test it in conjunction with tPA or other treatments.