Time and infarct size key to functional recovery after thrombectomy for large-core stroke
A latest study at ISC 2019 shows that even patients with large-core stroke damage can have a good outcome after mechanical clot removal with endovascular thrombectomy (EVT), depending on the size of the infarct and time lapses between stroke onset and treatment.
“Outcomes in stroke patients treated with thrombectomy is affected by the size of the stroke – the larger the stroke, the worse the outcome,” said lead author Dr Amrou Sarraj from McGovern Medical School at The University of Texas Health Science Center, Houston, Texas, US.
Although the safety and efficacy of EVT have been established in patients with minimal infarct volume, its role in large infarct core — usually defined as ASPECT* score of <6 and CT perfusion score of >50 cc — remains uncertain as these patients were excluded in most clinical trials.
The current study combined cohorts from the prospective multicentre SELECT study and TREVO registry study which involved 2,453 stroke patients who underwent EVT, including 187 patients with ASPECT ≤5. [ISC 2019, abstract LB8]
In SELECT, 48 percent of patients with a small infarct core (<50 cc) showed good outcome (defined as functional independence as indicated by mRS** score of 0–2) at 90 days compared with 20 percent of those with large core (50–100 cc) and none for very large core (>100 cc; p-trend=0.031).
Further validation by combining data from TREVO showed similar results, with 45 percent, 29 percent, and 11 percent of patients with small-, large-, and very large-core stroke, respectively achieving a good outcome at 90 days (p-trend=0.018).
“That is a great breakthrough in the field … Only 35 percent of them had mild disability 3 months after the stroke, which was considered a good outcome,” commented Dr Miguel Perez-Pinzon, chair of ISC 2019 Programme Committee. “For each 10 cc increase in stroke size, the probability of only mild disability decreased by 27 percent.”
Secondary outcomes such as symptomatic intracranial haemorrhage and neurologic worsening also rose significantly with increasing infarct volume. So was the safety outcome of mortality, which was 4 percent, 30 percent, and 50 percent for small-, large-, and very large-core stroke, respectively (p-trend=0.009).
Furthermore, with increasing time lapsed after stroke onset, the benefit with thrombectomy progressively lessened — positive outcome declined by 5 percent for every hour of delay in patients with a large infarct core, according to Sarraj.
He also pointed out that unlike most studies which used simple CT brain imaging to determine infarct volume, the current study evaluated patients using CT imaging and CT perfusion (CTP).
“While CT ASPECT score detects hypodense tissue, CTP identifies regions of very low blood flow or volume. Thus, large core definition may differ between CT and CTP,” explained the researchers.
“The addition of perfusion imaging may help identify the best candidates who can benefit the most from thrombectomy procedure, which we implemented in the design of upcoming SELECT 2 trial,” Sarraj said.