SAN FRANCISCO – For the treatment of coronary artery in-stent restenosis, angioplasty with a drug-coated balloon (AGENT DCB; Boston Scientific) was superior to conventional balloon angioplasty in preventing target lesion failure at 1 year in a high-risk patient population.
Approximate 50% reductions in the rates of target lesion restenosis and target vessel myocardial infarction (MI) accounted for the superior findings with the AGENT DCB over conventional balloon angioplasty.
Robert Yeh, MD, of Beth Israel Deaconess Medical Center in Boston reported at the annual Transcatheter Cardiovascular Therapeutics congress. “This represented a 38% relative risk reduction as well as a 10% absolute risk reduction in the endpoint. The P value for superiority was 0.0063, highly statistically significant.”
In-stent restenosis is clinically challenging and accounts for about 10% of all percutaneous coronary interventions. “Sometimes these patients have multiple layers, and that could be a third or fourth layer of stent, something that we try to avoid,” he said.
Drug-coated balloons, which are not currently approved in the United States, can deliver drugs that inhibit blockages from reforming, “without leaving additional layers of metal behind,” he added. Such devices are already available in Europe and Japan.
AGENT IDE was a prospective, multicenter, superiority trial that randomly assigned 480 patients 2:1 to the AGENT DCB (n = 321) or to conventional balloon angioplasty (n = 159). Randomization occurred after successful pre-dilation of the target vessel.
The trial included patients with in-stent restenosis previously treated with a bare metal or a drug-eluting stent with lesion lengths < 26 mm (reference vessel diameter: > 2 mm to ≤ 4), and percent diameter stenosis of more than 70% if they were asymptomatic or of more than 50% if they were symptomatic. Patients were excluded if they had a recent ST-elevation MI, bifurcation, saphenous vein or arterial graft, or thrombus in the target vessel.
All received dual antiplatelet therapy for at least 1 month and then antiplatelet monotherapy for the duration of the trial. The primary endpoint was target lesion failure at 1 year, a composite of target lesion restenosis, target vessel-related MI, or cardiac death. More than 93% of patients in each arm were available for evaluation of the primary endpoint.
The two groups were well balanced at baseline: Approximate age was 68 years, 27% were women, and three quarters were White. Approximately 28%-32% had had a prior coronary artery bypass graft, 20%-22% had previous heart failure, and about 22% had a history of left main coronary artery disease. Half had diabetes, and about half had stable angina.
Multiple stent layers were common in 43% of each group. Stenosis diameter was about 65% at baseline for the two groups and was reduced to 22% post procedure.
Outcomes all favored AGENT DCB
In the AGENT DCB group, the technical success rate was 92.9% vs 89.3% for balloon angioplasty. Intravascular imaging was used during the procedure in 72.3% of DCB cases and in 76.7% of balloon cases.
Besides demonstrating a nearly 38% reduction in the primary endpoint of target lesion failure at 1 year for the DCB over conventional balloon angioplasty, DCB nearly halved the rate of target lesion revascularization and target vessel MI and was superior on other measures of clinical outcome.
*Hazard ratio, 0.49; 95% CI, 0.31-0.79; ** HR, 0.51; 95% CI, 0.27-0.95
There was no stent rethrombosis with the DCB vs 3.9% with the conventional balloon angioplasty. Of note, there were no differences between the groups in terms of cardiac or noncardiac death.
Subgroup analyses of the primary outcome in terms of sex, age, diabetes, vessel size, or single or multiple stent layers all trended in favor of AGENT DCB but were not statistically significant for interaction.
The study is being expanded to include 600 patients. This device is a US Food and Drug Administration–designated breakthrough device, “and this pivotal trial will be the primary evidence used to support FDA approval,” Dr. Yeh said. “And given the marked superiority over conventional balloon angioplasty, I believe that the AGENT DCB is likely to become an important new treatment option for patients with coronary stenosis in the United States.”
Long overdue
Róisín Colleran, MBBCh, of the Cardiovascular Research Institute Dublin at Mater Private Hospital in Ireland, the designated discussant, first congratulated Dr. Yeh and his coinvestigators on the study’s conduct and findings.
“This study is long overdue,” she said. As Dr. Yeh noted, about 10% of PCI procedures are done for in-stent restenosis, Dr. Colleran said, but in 2023, there is still no coronary drug eluting balloon approved for this indication in the US, despite the class 1 recommendation in the 2014 European guidelines.
She pointed to the trial results, saying they are “clear...a significant reduction in target lesion failure driven by halving in rates of both target lesion revascularization and target vessel MI.”
Strengths of the study are it is the largest of its kind to date, with 480 patients, conducted at 40 US centers, using device-specific endpoints. There was a “very high” intravascular imaging rate of 75% in a cohort with a high risk for in-stent restenosis, consisting of 50% of patients with diabetes and more than 40% with multiple stents.
“The main limitation is the choice of comparator,” Dr. Colleran said. Balloon angioplasty is inferior to both stenting and drug coated balloon therapy for treatment of in-stent restenosis but is the standard of care in the United States, she noted. “I think...for regulatory reasons this was the comparator chosen,” she said.
“I think the implications are clear,” Dr. Colleran added. “This trial should provide a basis for regulatory approval of the drug coated balloon treatment of in-stent restenosis in the U.S. and finally provide this as an available treatment option for such patients.”
Dr. Yeh reported receiving grant/research support from Abbott Vascular, BD Bard, Boston Scientific, Cook Medical, Philips Medical, and Medtronic, and consulting for Abbott Vascular, Boston Scientific, CathWorks, Elixir Medical, Infraredx, Medtronic, Shockwave Medical, and Zol. Dr. Colleran had no disclosures. The trial was supported by Boston Scientific.
A version of this article first appeared on Medscape.com.