Conference Coverage

Patient transfer before thrombectomy worsens stroke outcomes



– Drip and ship may not be the most time-effective way to treat acute ischemic stroke patients who are candidates for endovascular thrombectomy.

Results from two separate real-world, observational studies showed that acute ischemic stroke patients with large vessel occlusions amenable to mechanical thrombectomy had significantly worse clinical outcomes when their management path included a stop at a primary stroke center followed by transfer to a comprehensive stroke center that had the capacity to perform thrombectomy, compared with going straight to the thrombectomy site.

Dr. Michael T. Froehler, a vascular neurologist at Vanderbilt. Mitchel L. Zoler/Frontline Medical News

Dr. Michael T. Froehler

“Interhospital transfer was associated with significant delays to treatment and a significantly lower chance of a good outcome,” compared with patients taken directly from the site of stroke onset to a comprehensive stroke center that could perform thrombectomy, Michael T. Froehler, MD, said while presenting one of the two studies at the International Stroke Conference sponsored by the American Heart Association.

The findings show “the system of care has room for improvement. Patients with large vessel occlusions clearly do better when we get them to mechanical thrombectomy as quickly as possible,” said Dr. Froehler, a vascular neurologist at Vanderbilt University in Nashville, Tenn. Thrombectomy “has a more powerful treatment effect than TPA [tissue plasminogen activator] and we need to adjust our standard of care to best deliver” thrombectomy, he said in an interview.

Dr. Eric Smith, University of Calgary, Canada Mitchel L. Zoler/Frontline Medical News

Dr. Eric Smith

“We’ve made progress in reducing door-to-needle times for delivering TPA. Now we need a similar focus on thrombectomy. The challenge is to link the hospitals that do thrombectomy with the primary stroke centers that don’t do thrombectomy and implement transfer or bypass agreements so patients quickly get to the right hospital. That is part of the push to treat as many eligible stroke patients with thrombectomy as possible,” commented Eric Smith, MD, medical director of the Cognitive Neurosciences Clinic at the University of Calgary, Alta.

The study run by Dr. Froehler used data collected in the Systematic Evaluation of Patients Treated With Stroke Devices for Acute Ischemic Stroke (STRATIS) registry, which began in 2014 and has data for 984 acute ischemic stroke patients with large vessel occlusions treated by mechanical thrombectomy seen at any of 55 U.S. centers. The series included 445 (45%) patients first seen as a primary stroke center and then transferred to a comprehensive center and 539 (55%) who went directly to a comprehensive stroke center (direct patients). Prior to thrombectomy, 628 of all patients (64%) received TPA, with a roughly similar percentage in both the transferred and direct patients.

The data showed that the median time from symptom onset to revascularization was 202 minutes among the direct patients and 312 minutes among those first seen at a primary stroke center and then transferred, a statistically significant difference. The average time difference per patient between the two subgroups was 100 minutes, Dr. Froehler reported.

This difference in time to reperfusion led directly to significant differences in functional outcomes after 90 days measured on the modified Rankin Scale (mRS). The percentage of patients with a mRS score of 0 or 1 (an excellent functional outcome) was 38% for the patients first seen at primary stroke centers and 47% in direct patients, a 47% relative rise in excellent outcomes among the direct patients. The percentage of patients with a mRS score of 0-2, which identifies functional independence post stroke, was 52% among transferred patients and 60% in direct patients, a 38% relative improvement for this outcome among direct patients.

The second study of stroke transfer times and outcomes used data from 562 acute ischemic stroke patients with large vessel occlusions treated in the Providence Health & Services system in five western U.S. states during 2012-2016. Nearly half the patients required a transfer and the other half went directly to a center able to perform thrombectomy. The analysis used clinical outcomes scored on the mRS at the time of hospital discharge.

Dr. Jason W. Tarpley, a vascular neurologist in Santa Monica, California. Mitchel L. Zoler/Frontline Medical News

Dr. Jason W. Tarpley

Results from analyses that adjusted for baseline differences among the patients showed that patients who underwent an acute transfer were five times more likely to either die during their index hospitalization or be discharged moderately or severely disabled, compared with direct patients. Patients initially seen at a primary stroke center were more than three times more likely to have these adverse outcomes, compared with direct patients. Further analyses showed that transferred patients and those initially treated at a primary stroke center were also significantly more likely to be discharged to a hospice, inpatient rehabilitation facility, or a skilled nursing facility, compared with direct patients, reported Jason W. Tarpley, MD, a vascular neurologist with Providence Health & Services in Santa Monica, Calif.

“Right now, the big delay at primary stroke centers is the door-in door-out time,” commented Ryan A. McTaggart, MD, an interventional neuroradiologist at Rhode Island Hospital in Providence, the only comprehensive stroke center in Rhode Island. He helped organize a partnership with 14 primary stroke centers in Rhode Island that uses a streamlined imaging, treatment (with TPA), and transfer protocol that hacked dozens of minutes off transfer times and produced a median time from onset of symptoms to revascularization by thrombectomy of 184 minutes in patients first seen at a primary stroke center. This clocking blows past the 202 minute median for stroke onset to revascularization in the direct patients from Dr. Froehler’s study.

Dr. Ryan A. McTaggart Mitchel Zoler/Frontline Medical News

Dr. Ryan A. McTaggart

The best way to improve outcomes for large vessel occlusion patients is not to always bypass primary stroke centers but to make the primary centers more time efficient, Dr. McTaggart said in an interview. “Door-in door-out time is the key metric for primary stroke centers, and they must try to keep it to less than 45 minutes.”

Stroke transport and treatment networks are now undergoing refinement in Tennessee, said Dr. Froehler, based in part on the data he reported. Considerations in Tennessee include how EMS workers assess possible stroke patients, decisions by EMS on where to take patients, and how quality of care is measured at primary and comprehensive stroke centers.

The STRATIS registry is sponsored by Medtronic. Dr. Froehler is a consultant to Medtronic, Blockade, Stryker, and Control Medical. Dr. Smith, Dr. Tarpley, and Dr. McTaggart had no disclosures.

On Twitter @mitchelzoler

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