Mechanical removal of blood clots reduced post-stroke disability in nearly half of “all-comer” real-world stroke patients in a global study, according to preliminary late-breaking research presented at this year’s International Stroke Conference (ISC 2022; 9–11 February, New Orleans, USA).
“This study shows how much stroke thrombectomy has advanced,” said lead study author Raul Nogueira (University of Pittsburgh School of Medicine, Pittsburgh, USA). “We saw a wide range of cases, including patients who, not too long ago, would not be considered good candidates for thrombectomy based on older age, pre-existing disability or large size of the stroke on presentation. Our findings in this study expand thrombectomy to be considered for more stroke patients.”
Previous studies have found that stroke patients who received mechanical clot removal had less disability after three months than those who did not. However, according to an American Heart Association (AHA) press release, these studies were performed in carefully selected centres and employed strict clinical and imaging inclusion criteria—which decreases the generalisability of their findings.
To examine the effectiveness of blood-clot removal across a wide range of stroke patients seen in routine daily care, i.e., outside of a clinical trial, the EXCELLENT (Embotrap extraction and clot evaluation and lesion evaluation for neurothrombectomy) trial enrolled 1,000 adult ischaemic stroke patients (average age=70, 52% female) at 36 sites worldwide, from September 2018 to March 2021. The sites were a mix of thrombectomy-capable and comprehensive stroke centres. Patients were treated with a specific mechanical thrombectomy device called Embotrap (Cerenovus) in an unlimited time frame in the trial.
The study was designed to collect real-world treatment and did not exclude patients based on pre-stroke independence level, severity of stroke, location of the occlusion, or time between onset of stroke and treatment, researchers said. As per current guidelines, mechanical thrombectomy treatment can be used within 24 hours of symptom onset in select patients. In addition, the study analysed the characteristics of the removed blood clots and how that impacted stroke recovery.
The EXCELLENT trial found that most of the patients required only one attempt to remove the blood clot. However, it is common to require multiple attempts to completely remove the clot. In nearly half of all patients, clot removal resulted in slight/minimal disability (able to look after own affairs without assistance or no worsening from their pre-stroke condition), as gauged by a standard scale measuring level of disability 90 days after stroke.
The study also found blood clots that were rich in red blood cells and low in platelets resulted in less disability than blood clots composed of less red blood cells, or those rich in red blood cells and high in platelet content. In this study, only 10% of patients whose clots had a higher composition of red blood cell count and a lower composition of platelets died within 90 days, compared to 24% of patients whose clots had a lower composition of red blood cells and platelets. Among patients with higher red blood cell content, 63% with lower platelet content had either slight or no disability, compared to 51% with higher platelet content.
“We knew that fibrin was associated with more difficult clot removal. However, this novel observation that platelets may modify clot properties is very intriguing,” Nogueira added. “The results may have potential implications for technique and device selection when removing clots and the development of better blood-clot removal strategies.”