At 6 months follow-up, a new-generation resorbable stent with a magnesium scaffold appears to perform at a level comparable to nonabsorbable drug-eluting stents (DES), according to first-in-man results presented as a late-breaker at the Cardiovascular Research Technologies conference, sponsored by MedStar Heart & Vascular Institute.
“IVUS [intravascular ultrasound] assessment demonstrated preservation of the scaffold area from post procedure up to 6 months with a low mean neointimal area,” reported Michael Haude, MD, PhD, director of the Heart & Vascular Center, Neuss, Germany.
Neointimal formation and late lumen loss (LLL) have been the Achilles’ heel of previous efforts to develop a viable fully absorbable stent, making these 6-month data highly encouraging.
The tested device is the most recent iteration of the DREAMS (drug-eluting resorbable magnesium scaffold) technology. Relative to DREAMS 2G, the DREAMS 3G device has several design changes, including a higher radial force and reduced strut thickness.
The goal was to build on the promise of DREAMS 2G while avoiding its limitations.
“The problem with DREAMS 2G was that it showed low–target lesion failure and scaffold thrombosis rates in multiple trials, but in-scaffold LLL was not comparable to LLL values observed with historical PLLA [poly-L-lactic acid]–based scaffolds or contemporary DES,” Dr. Haude said.
The 6-month data with DREAMS 3G were drawn from the BIOMAG-I study. Patients with stable or unstable angina were enrolled if they had no angiographic evidence of thrombus at the target lesion. Patients were also required to have no more than two single de novo lesions requiring revascularization.
Of 116 patients enrolled, 115 were available for evaluation at 6 months. The study was not controlled, but outcomes were compared at 6 months to those observed with the DREAMS 2G device in the BIOSOLVE-II trial, published several years ago in the Lancet.
For the primary outcome of in-scaffold LLL at 6 months, the mean LLL from baseline at 6 months was more than 50% lower with the DREAMS 3G device in BIOMAG-I than DREAMS 2G in BIOSOLVE-II (0.21 vs. 0.44 mm). In a post hoc superiority analysis employing a weighted mean, a superiority analysis supported a highly significant difference in favor of the newer device (P < .0001).
More importantly, the low LLL in BIOMAG-I was not just favorable relative to previously evaluated bioabsorbable stents, but it appears to compete with nonabsorbable options at least after this length of follow-up.
In terms of LLL at 6 months, “these data suggested that DREAMS 3G “is now on the level of contemporary DES,” Dr. Haude said.
The relative difference in favor of DREAMS 3G was even greater at 6 months for the secondary endpoint of in-segment LLL (0.05 vs. 0.27 mm) with similar significance for the superiority margin in a post hoc analysis (P < .0001).
Serial optical coherence tomography (OCT) was conducted post procedure, and indicated that the struts “were well embedded in the vessel wall,” according to Dr. Haude. Only 4.4% of struts on average were malapposed. The total incomplete strut apposition area was on average 0.08 mm. At 6 months, most struts were no long discernible on OCT, documenting device resorption.
Clinical results at 6 months were supportive. There were no cases of definite or probable scaffold thrombosis, and there were no target vessel myocardial infarctions or cardiac deaths. There was one clinically driven target lesion revascularization.
DREAMS 3G has other features designed to make it easier to deploy, Dr. Haude said. For example, radiopaque markers are now situated on both ends of the stent, making it easier to see on imaging. There are also plans to make these stents available in 15 sizes to accommodate a broad range of anatomy.
The data were impressive for many of the panelists invited to discuss the results.
“For the first time, we are seeing a bioabsorbable device showing excellent healing and very little late lumen loss,” said Michael H. Joner, MD, professor of early clinical trials at the German Center for Cardiovascular Research, Munich. “The next step is some sort of direct comparison with a drug-eluting stent.”
Describing himself as “a little more skeptical,” Aoke V Finn, MD, medical director and chief scientific officer, CVPath Institute, University of Maryland, Baltimore, said he wants to know more about the speed of device degradation and to see more long-term results in terms of clinical events. Although he considers the data promising so far, he considers it too early to embark on a randomized trial.
Longer-term data are coming, according to Dr. Haude. In addition to the 12-month follow-up that will include OCT and IVUS evaluations, there are annual clinical follow-up analyses planned to 5 years.
Dr. Haude reports financial relationships with Biotronik, Cardiac Dimensions, OrbusNeich, and Philips. Dr. Joner reports no potential conflicts of interest. Dr. Finn reports financial relationships with 19 pharmaceutical companies including those that manufacture cardiovascular stents.