In the past six months, stroke care in the United States has taken an epoch-changing turn. Techniques, technologies, and treatment pathways hinted at in earlier trials have become fully vetted and are a new gold standard giving doctors more time to treat stroke patients and help them regain pre-stroke capabilities.
"I guess the best thing I can say is we have altered our practice here, essentially immediately, based on the results of those studies. I guess that shows we believe it," said William Powers, M.D., chairman of the neurology department at the University of North Carolina.
Powers's words might carry extra weight because he also chaired the group that wrote new guidelines for stroke treatment for the American Heart Association/American Stroke Association, announced in January. The new guidelines highlight some of the results of the newest trials, which showed some patients suffering ischemic strokes may now benefit from treatment, in particular mechanical thrombectomy, up to 16 and even 24 hours after the onset of symptoms, up from a six-hour window previously.
"The 'Sorry, too late' stories now are going to be fewer and fewer," Powers said of patients who previously would have been classified as non-treatable due to exceeding the old time limits. "It may still be too late, they may fail the imaging tests, but we can at least try to see if there is something we can do to help them."
Thrombectomy to Thrive
The new guidelines, trial results, and FDA approvals for mechanical thrombectomy technology signal a coming surge in demand for the procedures and trained specialists who perform them. In fact, Kaila Krum, an equity analyst at financial services firm William Blair & Co., estimated the mechanical thrombectomy market at present is only 15% penetrated and can grow at better than a 20% pace for the next two to three years.
Krum made those comments in research accompanying the firm's initiation of coverage of Alameda, CA-based Penumbra. The company's aspiration-based system competes with several other devices, such as Kalamazoo, MI-based Stryker's Trevo stent retriever. As one might surmise, the aspiration system creates a low-pressure vacuum to suck a clot out of its location, while the stent retriever uses a mechanism to pull it out. However, both are inserted into a guide catheter, and according to the COMPASS trial, led by Aquilla Turk, D.O., director of the stroke and cerebrovascular program at the Medical University of South Carolina and principal investigator of the trial, outcomes of each technique result in a "pick 'em" situation for clinicians.
"If you look at the technique we use with aspiration, it's not a competitor to the stent retriever," Turk said. The trial results showed outcomes of the technique, dubbed ADAPT (A Direct Aspiration, First Pass Technique), were virtually identical to outcomes of thrombectomies performed with the stent retrievers. Turk said he's had many cases in which aspiration opens the affected blood vessel within five minutes of the insertion of the catheter in the groin.
"We'll try that two or three times and if it doesn't open it, then at that point, through the aspiration catheter, you can put a stent retriever," Turk said. "If you do that approach, and do it in that sequence, we find we are about 95% effectively getting the blood vessels open in a fast and efficient manner."
Regional Organizations Must Emerge
If outcomes of the techniques and technologies used to perform thrombectomies may be virtually identical, the larger organizational issues of where mechanical thrombectomy expertise will thrive are much more vexing.
"You need to be able to do it 24/7, and you need to have people on call who can come to the hospital very quickly and that means having a critical mass of people," Powers said. "But then you need a critical number of procedures to keep them busy, and that's where it gets tricky. Every hospital won't be able to do this.
"So we are going to have to develop regional systems of care that can move people quickly to the place they need to be. When you first take a look at this you say, 'That's easy, let's just take those patients to the big hospital that can do it.' The problem is, many of those hospitals can't take every stroke patient and decide if they need mechanical thrombectomy. So we need to set up a distributed system that moves people where they need to go."
Turk said a critical time in the new treatment model will be earlier identification of patients who might benefit from mechanical thrombectomy. Within hospitals capable of performing the procedures, Turk said process improvements such as bypassing emergency departments and taking the patient directly to the angio suite will be perfected.
The larger area of improvement, which will take far more inter-organizational coordination, will entail setting up communications between hospitals that share service areas and equipping first responders with better training and technology.
"I think there is going to be a paradigm shift here in the next couple of years, where we will focus on getting the right patients from when they are identified in their home," he said. "Right now, l often rely on EMS personnel, many of whom are volunteers, who may not have a lot of formal training."
Turk cited another study in which MUSC staff participated, VITAL, which tested portable diagnostic technology from Pleasanton, CA-based Cerebrotech, which measures bioimpedence asymmetry, a measure of the electrical characteristics of the brain.
"That's the type of tool, I think, will really change the landscape," Turk said. Combined with the process improvements the top-performing hospitals will design, he said, "it'll save at least an hour, if not two, from when that patent gets identified in their home to when they get their groin stuck to get that thrombectomy."