Abu Dhabi, United Arab Emirates — The use of a balloon guiding catheter was associated with worse functional outcomes than the use of a conventional guiding catheter in stroke patients with prior great vessel 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 16th World Stroke Congress (WSC) 2024.

Safety concerns

In presenting the study results, study investigator Pengfei Yang, MD, Neurovascular Center, Changhai Hospital/Shanghai University of Science and Technology, Shanghai, China, said there is uncertainty about the use of balloon-guided catheters for mechanical thrombectomy in stroke patients acute ischemic. It is believed that the use of a balloon guiding catheter can reduce distal emboli, improve the quality of reperfusion, shorten procedure time, and improve functional outcome.

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

The investigator-initiated study had a prospective, randomized, open-label, endpoint-blinded 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 participants had a mean National Institutes of Health Stroke Scale score of 15 and an Alberta Stroke Program Early CT Score of 8. The median time to onset of stroke symptoms was 6 hours.

The primary outcome was functional status as determined by the modified Rankin Scale (mRS) change analysis at 90 days. This suggested a worse outcome in the balloon guide catheter group, with an adjusted 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 the study’s limitations 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 with a high incidence of intracranial atherosclerotic disease.

He concluded that further research is needed to understand whether there is a role for balloon guiding catheters in accidental thrombectomy.

Attempting to reduce distal embolization

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

“Because they were looking for an effect size of about 10%, 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. Ultimately, there was no clear statistical difference in safety outcomes,” he said.

Hill explained how a balloon guide can 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 the flow to stop temporarily, then the stent retriever is used to pull the thrombus back into the guiding catheter.

“With no forward flow, there is little chance of distal embolization of the thrombus and everything can be captured in the guiding catheter. Then the balloon is deflated and the full restoration is done.”

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

Hill noted that some interventionalists use this balloon-guided 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 stopped early, mainly due to futility, but there was a nonsignificant increase in mortality (8% increase in absolute risk). He also noted that the study used first-generation balloon guiding catheters, and he’s not sure if the newer technology would be better.

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