Some patients with large ischaemic core on CT may benefit from endovascular thrombectomy (EVT) but clinicians will have to wait for more definitive evidence, an Australian stroke specialist says.
An analysis of a subgroup of patients with large ischaemic core from the SELECT study has found no significant difference between patients who received the intervention and those who received only medical management.
The study, published in JAMA Neurology, found 31% of 62 patients who received EVT achieved functional independence (a modified Rankin Scale score of 0-2) within 90 days compared to only 14% of 43 patients who just received medical management.
However the patients were not randomised to either arm – the decision to perform EVT was at the discretion of local investigators – and there were important differences between their baseline characteristics such as time to arrival at hospital.
“These nonrandomized data suggest better rates of functional independence with EVT and a shift toward better overall 90-day mRS scores. These benefits, however, did not reach significance after adjusting for baseline imbalances. The small sample size limits the power of this analysis,” the study authors said.
It found no significant differences between the groups in terms of death, neurological worsening or symptomatic ICH.
However the study was able to demonstrate that the likelihood of a good outcome with EVT declined as the volume increased – a decline of 42% for every 10 cm3 increase in ischaemic core volume.
“These data suggest reasonable rates of functional independence in patients with ischemic core volumes of 50 to 100 cm3. In 10 patients with volumes greater than 100 cm3, no functional independence was observed with EVT.”
The likelihood of functional independence also dropped by 40% for every hour delay in time to treatment.
An editorial in the journal by Professor Bruce Campbell, from Royal Melbourne Hospital, said the limits of benefit of endovascular thrombectomy in patients with large ischaemic core volumes remain to be determined.
“A key consideration in patients with a large ischemic core is that mRS scores of 0 to 2 may not be the best definition of treatment success. If a patient achieves an mRS score of 3 and lives at home with some assistance to cook or clean, that is highly preferable to dying or requiring nursing home care (mRS scores, 5-6),” he said.
While clinicians await more data from ongoing randomised controlled trials, he said it was clear that some patients with large ischaemic core were likely to benefit from early EVT.
“The key modifying considerations are the patient’s functional status, location of the core, and the expected time to reperfusion.”
“A patient with a large ischemic core who has presented directly to an endovascular-capable hospital is therefore substantially more likely to benefit than a patient who requires a prolonged interhospital transfer.”
He added that the risk of symptomatic hemorrhagic transformation was likely greater in patients with a large ischaemic core, but may not affect the risk-benefit analysis given their natural history was so poor.