Uncertainty Over Balloon Guide Catheter Use for MT in Stroke

Abu Dhabi, UAE — Use of a balloon guide catheter was associated with worse functional outcomes than use of a conventional guide catheter in stroke patients with large vessel anterior occlusions undergoing thrombectomy within 24 hours of symptom onset 

However, the PROTECT-MT trial was stopped early, and the small sample size limited the precise estimate of the treatment effect.

The findings were reported on October 23 at the 16th World Stroke Congress (WSC) 2024.

Safety Concerns

Presenting the trial results, study investigator, Pengfei Yang, MD, Neurovascular Center, Changhai Hospital/University of Shanghai for Science and Technology, Shanghai, China, said that uncertainty exists over balloon guide catheter usage for mechanical thrombectomy in patients with acute ischemic stroke. It is thought that the use of a balloon guide catheter may reduce distal emboli, improve reperfusion quality, shorten procedure time, and improve functional outcome.

The trial was conducted to compare the effectiveness of a balloon guide catheter with that of a conventional guide catheter on functional outcomes in patients with acute ischemic stroke and treated with thrombectomy.

The investigator-initiated trial had a prospective, randomized, open-label, blinded-endpoint design and aimed to enroll 1074 patients. However, the data and safety monitoring board recommended suspension of recruitment due to safety concerns after 329 patients had been randomized. Baseline characteristics showed that the participants had a median National Institutes of Health Stroke Scale score of 15 and an Alberta Stroke Program Early CT Score of 8. The median time from onset of stroke symptoms was 6 hours.

The primary outcome was functional status as determined by the shift analysis of the modified Rankin Scale (mRS) at 90 days. This suggested a worse outcome in the balloon guide catheter group, with an adjusted common odds ratio of 0.66 (95% CI, 0.45-0.98; P = .037).

Dichotomized mRS results showed scores of 0-3 in 41% of the balloon guide catheter group and 56% of the conventional guide catheter group (odds ratio [OR], 0.56; 95% CI, 0.35-0.88) and scores of 0-4 in 57% of the balloon catheter group and 73% of the conventional catheter group (OR, 0.47; 95% CI, 0.28-0.78).

Other observations included comparable new territory embolization, reperfusion quality, and first-pass effects in the two groups but an increased procedure time in the balloon catheter group, Yang reported. There was also an increase in severe vasospasm in the internal carotid artery in the balloon catheter group (4% vs 0.6%).

Yang noted that limitations of the trial included its early termination and small sample size, variability in treatment devices and operator experience, and the fact that it was conducted in an area where there is a high incidence of intracranial atherosclerotic disease.

He concluded that further research is necessary in order to understand whether there is a role for balloon guide catheters in stroke thrombectomy.

Trying to Reduce Distal Embolization 

Commenting on the results for Medscape Medical News, Michael Hill, MD, professor of neurology at the University of Calgary, Calgary, Alberta, Canada, said the study is inconclusive.

“Since they were looking for about a 10% effect size, the futility simply means that if there is an effect of using a balloon guide catheter it is likely to be less than 10% absolute risk difference. Finally, there was no clear statistical difference in safety outcomes,” he said.

Hill explained how a balloon guide may be helpful in the thrombectomy procedure.

He went on to explain that the hypothesis behind the balloon guide approach is to reduce distal embolization.

“The theory is that the balloon is inflated in the distal internal carotid artery, causing temporary flow arrest, then the stent retriever is used to pull back the thrombus into the guide catheter.

“With no forward flow, there is a reduced chance of distal embolization of the thrombus, and it can all be captured in the guide catheter. Then the balloon is deflated, and full restoration is achieved.”

The issue of distal control is important, said Hill. Both stent retrievers and aspiration techniques carry the risk of causing a thrombus to fracture, leading to distal embolization.

Hill noted that some interventionalists use this balloon guide catheter approach, but it is not routine practice and there are conflicting observational data on its benefits.

He pointed out that the current trial was halted early, essentially because of futility, but there was a nonsignificant increase in mortality (8% absolute risk increase). He also noted that first-generation balloon guide catheters were used in the study, and it is uncertain whether newer technology would be better.

The PROTECT-MT trial was funded by the Shanghai Hospital Development Center, the Biopharma Industry Promotion Center Shanghai, and Tonbridge Medical Technology Co. Yang and Hill reported no relevant disclosures.