LOS ANGELES — When patients with acute ischemic stroke are treated with stent retriever-based reperfusion within 150 minutes of symptom onset, they have a more than 85% rate of functional independence. This rate, however, falls sharply every hour thereafter.
“Time to treatment continues to be an important determinant of good outcome and should be incorporated into quality metrics,” Ashutosh P. Jadhav, MD, PhD, study investigator from the University of Pittsburgh Medical Center, told Neurology Advisor.
The subanalysis results of the SWIFT PRIME trial were presented here at the 2016 International Stroke Conference.
In the global, prospective, randomized SWIFT PRIME trial, investigators observed improved outcomes among patients with disabling acute ischemic stroke who received endovascular therapy with a stent retriever (Solitaire, Covidien) plus intravenous tissue plasminogen activator (IV tPA) compared with IV tPA alone.
For the present substudy, Dr Jadhav and fellow researchers of the SWIFT PRIME trial aimed to better understand the association between functional independence and time to reperfusion in participants who received thrombectomy.
“Previous studies have indicated that fast recanalization with pharmacological or mechanical clot disruption leads to a higher likelihood of functional independence,” Dr Jadhav said. “A unique feature of the SWIFT PRIME trial design was to establish aggressive time metrics with frequent feedback to study sites. This allowed close monitoring of workflow and early recognition of potential bottlenecks.”
The final analysis included 83 patients who received substantial reperfusion — defined as thrombolysis in cerebral infarction score of 2b or 3 — with thrombectomy. The researchers examined how time from stroke onset to reperfusion and from qualifying imaging to reperfusion impacted independent outcome, defined as a modified Rankin Scale score of 0 to 2.
Overall, 88% of patients achieved substantial reperfusion.
Dr Jadhav and colleagues observed a marked effect of time to reperfusion on rate of functional independence. Specifically, while the rate of functional independence was 87% for patients who received reperfusion 150 minutes from symptom onset, this rate decreased by 10% during the next 60 minutes of delay in onset to reperfusion and by 15% with every 60-minute delay thereafter.
In addition, among patients presenting directly to study hospitals, faster post-arrival workflow speed yielded improved outcomes.
“Our analysis has demonstrated overall fast workflow in this trial compared to [the Interventional Management of Stroke (IMS) III trial],” Dr Jadhav said.
Although the workflow was fast in SWIFT PRIME once patients arrived to the destination emergency department, the present analysis did demonstrate significant delays in inter-facility transfer times, Dr Jadhav said.
“This appears to be the most substantial bottleneck in delivering endovascular therapy, and future studies will be necessary to improve pre-hospital triage and inter-facility transfer times,” he said. “Optimal patient outcomes and resource utilization will be predicated on getting the right patient to the right place. This will require patient education and collaboration with [emergency medical] services.”
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Goyal M, Jadhav AP, Bonafe A, et al. Abstract 2. Good Outcome After Successful Recanalization Is Time Dependent In The Swift Prime Randomized Controlled Trial. Presented at: International Stroke Conference; Feb. 16-19, 2016; Los Angeles.