Patrice Wendling

June 01, 2017

PARIS, FRANCE — A thin-strut stent that elutes sirolimus months after the polymer coating is gone was judged to be noninferior to an already-marketed everolimus-eluting stent at 1 year in an all-comers population[1].

Among more than 1400 patients, target lesion failure—a composite of cardiac death, target vessel MI, and clinically indicated target lesion revascularization at 12 months—occurred in 5.8% of patients treated with the MiStent (Micell Technologies) and 6.5% treated with the Xience stent (Abbott Vascular) (noninferiority P<0.001).

There were no differences in any of the individual components of the primary end point between devices, and the MiStent remained noninferior across multiple patient subgroups, co–principal investigator Dr Robbert de Winter (Academic Medical Center, Amsterdam, the Netherlands) reported on behalf of the DESSOLVE III investigators in a late-breaking trials session here at EuroPCR 2017.

MiStent is investigational in the US but has been commercially available in Europe since June 2013.

During a press briefing highlighting the study, de Winter explained that the rationale behind the novel stent is that durable polymers, coated on a stent and present in the vessel wall for a longer period of time than the drug elution, may induce inflammation and eventually lead to intimal growth, restenosis, and new atherosclerosis.

The MiStent has a bioresorbable poly-L-lactic acid polymer that is absorbed within 3 months and coated with a microcrystalline depot of sirolimus that embeds in the vessel wall and remains for up to 9 months. "In theory, you would expect that any inflammatory response from the coating to be counteracted by the drug," he said.

Panelist Dr Robert Byrne (German Heart Centre, Munich) said, "For me, this is a potentially interesting device. It's the only device where we have a drug elution that's more prolonged than the polymer, and this does offer the potential perhaps for later benefit as we talk about late catch-up and subsequent events."

Byrne, who headed the European Society of Cardiology/European Association of Percutaneous Cardiovascular Interventions 2015 task force for the evaluation of new coronary drug-eluting stents, said, from a regulatory standpoint, MiStent "ticks a lot of boxes" with a successful first-in-human study, a modest angiographic end point study where late lumen loss looked good, and now a clinical-end-point study.

"This is what we want to see in the regulatory space for the stents that we use to treat our patients day in and day out," he said.

Byrne remarked that the study's 4% noninferiority margin was "quite generous" but that the generalizability of the data is "likely to be high," as 25% of patients had diabetes, 60% had acute coronary syndrome, and 1.5 lesions were treated per patient.

DESSOLVE III was conducted at 20 European sites and randomly assigned 703 patients to MiStent and 695 to the Xience stent. Dual antiplatelet therapy was given for 6 months for patients with stable angina and 12 months for those with ACS, as per clinical guidelines.

Definite stent thrombosis was very rare with the MiStent and Xience devices (0.4% vs 0.7%; P=0.480).

Target lesion revascularization rates began to diverge after 6 months and numerically favored MiStent over Xience (2.6% vs 3.8%), de Winter noted.

An optical coherence tomography (OCT) substudy in 60 patients, also presented at the meeting, showed less late lumen loss in the MiStent-treated patients than in the Xience-treated patients.

Panelist Dr Chaim Lotan (Heart Institute, Hadassah Medical Center, Jerusalem, Israel) said the study provides a "very small sign for superiority" for late restenosis with MiStent and pointed out that strut thickness, a very strong predictor of restenosis, is just 64 µm with MiStent vs 81 µm with Xience.

"This fact is a major fact in the comparison between the two stents, and I cannot say whether it's the sirolimus or the strut by itself, but definitely it's another good stent on the shelf," he said.

The study was sponsored by the European Cardiovascular Research Institute with grants from Micell Technologies and Stentys. De Winter reports receiving research/grant support from OrbusNeich Medical, Abbott Vascular, AstraZeneca, Stentys, and Tryton. Byrne reports serving on a speaker's bureau for Biotronik. Lotan reports honoraria or consultation fees from Cordio Medical.

Follow Patrice Wendling on Twitter: @pwendl. For more from theheart.org, follow us on Twitter and Facebook.

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