Speed is key for stroke thrombectomy
medwireNews: Early initiation of endovascular stroke treatment is critical to give patients the best chance of achieving functional independence, say the HERMES collaborators.
“The profound effect of early time to treatment suggests that systems must change substantially to achieve the maximum benefit for the most patients”, write Steven Warach and S Claiborne Johnston, from the University of Texas at Austin, USA, in an editorial in JAMA, where the study is published.
The research, by Michael Hill (University of Calgary, Alberta, Canada) and colleagues, found that the average modified Rankin Scale (mRS) score at 3 months was 2.9 among patients who received endovascular treatment plus medical therapy, compared with 3.6 among those given medical therapy only.
The 1287 patients were treated in five randomised trials and were given intravenous thrombolysis if eligible (83 and 87% of the endovascular and medical therapy groups, respectively).
The corrected odds ratio (OR) for patients being less disabled after endovascular versus medical treatment was 2.49 overall. However, this was dependent on the time between symptom onset and arterial puncture, with ORs of 2.79 at 3 hours, 1.98 at 6 hours and a nonsignificant 1.57 at 8 hours. Likewise, the corresponding absolute risk differences fell from 39.2% to 30.2% and 15.7%.
Patients’ chances of achieving functional independence (mRS 0–2) were also significantly influenced by time to arterial puncture, but their chances of survival were not. And the findings were mirrored in 390 patients in whom substantial reperfusion was achieved; mRS scores and the chances of achieving functional independence declined with increasing delay to arterial puncture, with mortality unaffected.
Among these patients, there was a 64.1% chance of functional independence at 3 months if arterial puncture occurred 180 minutes after symptom onset, but just a 46.1% chance if it occurred at 480 minutes.
But although the efficacy of endovascular treatment reduced with increasing treatment delay, the team did find significant benefits right out to 7 hours and 18 minutes after symptom onset.
“Expansion of the time window would make the benefit of this treatment accessible to more patients, albeit at the tail of the efficacy curve”, say Warach and Johnston.
“These data have important implications for how stroke services should be organized, including the time at which thrombectomy should not be attempted.”
In addition to “substantial system changes”, the editorialists say that research is needed to determine the optimal balance between speed of reperfusion and transporting patients to the most expert centres, and to assess out-of-hospital strategies for ensuring prompt treatment.
medwireNews is an independent medical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2016