乌鸦传媒

Faster procedural times are key to thrombectomy after a large-vessel ischemic stroke, investigators suggested once again.

Overall, meta-analysis of five trials showed better average modified Rankin Scale scores at 3 months among stroke patients receiving endovascular therapy (2.9 versus 3.6 for medical therapy cohort), according to , of Canada's University of Calgary, and fellow HERMES collaborators.

But post-intervention outcomes were less likely to beat medical therapy the longer it took for patients to get from symptom onset to arterial puncture, they reported online in the :

• 3 hours (common odds ratio [cOR] 2.79, 95% CI 1.96-3.98)
• 6 hours (cOR 1.98, 95% CI 1.30-3.00)
• 8 hours (cOR 1.57, 95% CI 0.86-2.88)

The cut-off time for endovascular therapy to show statistically significant benefit was 7 hours and 18 minutes.

"Benefit was greatest with time from symptom onset to arterial puncture for thrombectomy of under 2 hours and became nonsignificant after 7.3 hours," the authors concluded.

Even among patients who got substantial reperfusion with thrombectomy, the odds of residual disability were less favorable with every hour of delay to reperfusion (cOR 0.84, 95% CI 0.76-0.93). The same was true for functional independence (cOR 0.81, 95% CI 0.71-0.92).

No advantage in 3-month mortality or symptomatic intracranial hemorrhage was observed with faster reperfusion, however.

Even so, "we need to do better at determining how best to identify the appropriate patients for direct transport to a comprehensive stroke center. It is not known at this time how exactly to do this, but we need to make it a high priority to figure it out. Our communities are depending on us to do so," commented , of MedStar Washington Hospital Center in Washington, D.C., in an email to 乌鸦传媒.

Hill and colleagues performed a meta-analysis of five studies that randomized patients to medical therapy with or without endovascular thrombectomy (n=653 and n=634, respectively).

The endovascular group was less likely to receive IV tissue plasminogen activator (tPA, 83% versus 87% for the medical therapy group, P=0.04). This and other imbalances in patient and procedural characteristics were a potential source of bias, the investigators acknowledged.

"The effects of thrombectomy in reducing disability and restoring functional independence were remarkably robust and consistent across five independent trials, notwithstanding trial differences in time-to-treatment windows and imaging selection criteria," according to , and , both of The University of Texas at Austin.

As for earlier thrombectomy, they wrote in an accompanying editorial that it can be achieved with "substantial system changes."

For example, they wrote, "Organizations that certify stroke centers may attempt to help improve outcomes by requiring endovascular-capable stroke centers to meet aggressive goals, such as 60 minutes from hospital arrival to arterial puncture and 90 minutes from hospital arrival to achievement of substantial reperfusion."

Transferring patients to endovascular-capable stroke centers also needs to become more common -- and faster, Warach and Johnston recommended.

"If the referring facilities are linked to receiving facilities by video telecommunication and routinely include vascular imaging (CT angiography) for assessing eligibility for thrombectomy by the receiving team, redundant assessments and delays may be eliminated at the receiving hospital (where the patients could be transported directly to the angiography suite), potentially saving an estimated 30 to 45 minutes," they wrote.

"The biggest opportunities to improve outcomes through time reductions may involve the emergency medical system (EMS) ... but these opportunities also pose the biggest challenges," they commented.

"Throughout the country EMS directors and personnel are debating the best protocols to triage patients directly to endovascular capable facilities: Which out-of-hospital stroke scale to use for identifying large artery occlusions? Would telemedicine directed by a remote stroke physician be a better triage technique? Should primary stroke centers be bypassed to transport patients to comprehensive centers, even if it means delaying the start of IV tPA? How much delay in bypass is acceptable? How much of a delay to start IV tPA would eliminate the benefit of earlier thrombectomy? Would a mobile stroke unit with CT angiography and out-of-hospital tPA administration be the best way to triage to comprehensive stroke centers for thrombectomy?"

Despite the spirited debates around these issues, a major barrier to answers appears to be the lack of a central organization with the authority to create and enforce standardized EMS transport protocols in the U.S, according to Warach and Johnston.