Recently presented results from the PROTECT-MT randomised controlled trial (RCT) have indicated worse functional outcomes following stroke thrombectomy with a balloon guide catheter (BGC) versus a conventional guide catheter. However, the study’s investigators believe these findings are unlikely to be fully conclusive, due to the fact the trial was halted early over safety concerns and subsequently only produced a small sample size for data analyses.
Pengfei Yang (Naval Medical University/Changhai Hospital, Shanghai, China), who delivered these findings for the first time at the 16th World Stroke Congress (WSC; 23–26 October, Abu Dhabi, United Arab Emirates), initially posited that “uncertainty exists” over BGC usage in mechanical thrombectomy treatments of patients with acute ischaemic stroke caused by anterior-circulation large vessel occlusion (LVO).
Against this backdrop, Yang and colleagues conducted the investigator-initiated, multicentre, prospective, open-label PROTECT-MT RCT with blinded-outcome assessments to ascertain the effectiveness and safety of BGC-based thrombectomy procedures for ischaemic stroke. The comparator in the trial was the use of conventional guide catheters in these procedures, and the primary endpoint was an ordinal shift analysis of scores on the modified Rankin scale (mRS)—a metric often deployed to determine a patient’s post-stroke functional outcome status—at 90 days.
According to Yang, an estimated 1,074 stroke patients—all of whom presented with temporary, proximal LVOs within 24 hours of symptom onset—met the inclusion criteria for PROTECT-MT and were randomised 1:1 to undergo a mechanical thrombectomy procedure utilising either a BGC (intervention group) or a conventional guide catheter (control group).
Recruitment for the trial began back on 7 February 2023. However, in November of the same year, the trial’s independent data and safety monitoring board (DSMB) held a meeting to review primary outcome data and would ultimately recommend the suspension of further recruitment into PROTECT-MT due to safety concerns. This suspension was implemented by the trial’s steering committee, with 329 patients having been randomised to that point, and the steering committee halted recruitment completely after these safety concerns “persisted” upon further review of the data in April 2024.
Presenting unblinded results from the trial at WSC 2024, Yang relayed that the use of BGCs was associated with inferior functional outcomes compared to use of conventional guide catheters in LVO ischaemic stroke patients receiving mechanical thrombectomy. Specifically, Yang and colleagues’ 90-day mRS shift analysis revealed an adjusted common odds ratio (OR) of 0.66 (95% confidence interval [CI], 0.45–0.98; p=0.037) suggesting worse outcomes in the intervention group. Dichotomised mRS results also showed that scores of 0–3 were achieved in 41% of patients in the BGC group compared to 56% in the conventional guide catheter group (OR, 0.56; 95% CI, 0.35–0.88), while scores of 0–4 were achieved in 57% of patients in the former group versus 73% in the latter (OR, 0.47; 95% CI, 0.28–0.78).
The PROTECT-MT investigators’ analyses uncovered several other notable observations, including the fact that rates of embolisation in new territories (ENT), reperfusion quality and first-pass effects were all comparable between the two study groups. However, Yang did report a longer average procedure time and an increased rate of severe vasospasm in the internal carotid artery (ICA) in patients treated with a BGC.
In addition to the study being terminated early and therefore only providing a final cohort that was roughly one third of the sample size the investigators had initially sought, Yang highlighted multiple other potential limitations. These included discrepancies in the types of devices used and in the experience levels of individual operators, as well as the fact PROTECT-MT was conducted solely at sites in China, where intracranial atherosclerotic disease (ICAD) is known to be a more common underlying cause of ischaemic stroke as compared to many other global regions.
As such—despite PROTECT-MT being the largest RCT to date attempting to assess the impact of BGCs versus conventional guide catheters on thrombectomy-related functional outcomes in LVO stroke patients—Yang concluded that further research will be necessary in order to fully elucidate the role for BGC usage in interventional stroke care.
The findings of PROTECT-MT have since been published in full in The Lancet.
