Ultrasound during surgery to unblock arteries safe and effective way to lower stroke risk: Study
Using ultrasound during surgery to unblock carotid arteries is a safe and effective way to significantly reduce the risk of stroke and death, finds a trial published by The BMJ today.
The technique, called sonolysis, uses continuous ultrasound directly on the artery to help break up blood clots during carotid endarterectomy - a procedure to remove fatty deposits from carotid arteries that supply blood to the brain, face, and neck.
Pilot studies have shown a potential positive effect of sonolysis on the risk of stroke during this type of surgery, so researchers wanted to test this in a randomised controlled trial.
Their findings are based on 1,004 patients (average age 68; 31% female) due to have carotid endarterectomy at 16 centres in three European counties (Czech Republic, Slovakia, and Austria) between 20 August 2015 and 14 October 2020.
A total of 507 patients were randomly assigned to the sonolysis group and 497 to the control group (sham sonolysis). All patients had carotid endarterectomy within 9 days of randomisation.
The main measure of interest was a combination of ischaemic stroke, transient ischemic stroke (TIA or ‘mini-stroke’), or death within 30 days of surgery, verified by a stroke neurologist.
Potentially influential factors such as age, sex, conditions such as diabetes and high blood pressure, medication use, and smoking history were also taken into account.
Eleven (2.2%) of patients in the sonolysis group experienced ischaemic stroke, transient ischemic stroke or death within 30 days of surgery compared with 38 patients (7.6%) in the control group - a statistically significant risk difference of 5.5%.
A total of 460 patients also received a brain scan before and one day after surgery: 236 in the sonolysis group and 224 in the control group. New brain lesions were detected in 20 (8.5%) patients in the sonolysis group and in 39 (17.4%) patients in the control group - a statistically significant risk difference of 8.9%.
Sonolysis was found to be safe, and 94.4% of patients in the sonolysis group were free from serious adverse events 30 days after the procedure.
However, death within 30 days and over the course of one year did not differ significantly between groups.
The exact way in which sonolysis helps prevent stroke remains unclear, but it’s thought that ultrasound waves can break apart blood clots and speed up fibrinolysis, the body’s natural anti-clotting process, explain the authors.
They acknowledge that the sonographer could not be blinded, as only standard ultrasound machines were used. However, they point out that patients and all other health professionals involved in the trial were unaware of the group assignments.
As such, they conclude that sonolysis “has the potential to make carotid endarterectomy safer with a higher benefit for patients with carotid stenosis compared with the best medical treatment, especially in patients with asymptomatic carotid stenosis.”
This trial has several strengths, but some questions surround the study design and results and should be considered before widespread adoption of this technique, says a US vascular surgeon in a linked editorial.
However, he adds that resolution of the above concerns, along with a cost effectiveness calculation, “can then inform whether this exciting new application of an established technology can improve care for patients undergoing carotid endarterectomy.”
