APPOSITION III: Self-Expanding Stent May Cut MACE, Deaths in AMI

Shelley Wood

March 12, 2013

SAN FRANCISCO — A self-expanding stent, designed to overcome the difficulty of correctly sizing a coronary stent in the setting of AMI, may help reduce rates of mortality and reinfarction in these acute patients, according to one-year results from the APPOSITION III trial.

Dr Gilles Montalescot (Pitié-Salpêtrière Hospital, Paris, France) presented the study here at the American College of Cardiology 2013 Scientific Sessions.

Explaining the "sizing dilemma" in STEMI, Montalescot noted that under- or oversizing the stent during AMI is common and can lead to adverse outcomes. Malapposition and underexpansion can promote stent thrombosis or restenosis, while overdilation of the stent can cause dissections and perforations or no reflow.

The Stentys self-apposing stent is made of nitinol with disconnecting struts that allow for side-branch access and is deployed via sheath retraction, rather than balloon expansion, so that the stent itself expands to fit the vessel, continuing to shift as the vessel-wall diameter adjusts in the periprocedural period.

For APPOSITION III, 965 patients at 50 centers in 14 countries were treated with the self-expanding stent (either a bare stent or a paclitaxel-eluting version, at the operator's discretion).

Dr Gilles Montalescot

At one year, the rate of major adverse cardiac events (MACE, defined as cardiac death, target vessel re-MI, emergent bypass, or clinically driven target vessel revascularization [TVR]) was 9.3%. Cardiac death was 2%, and target vessel MI was 1.3%.

MACE rates were even lower when postdilation was performed, as recommended by the stent manufacturer (8.4%), compared with 11.3% in patients who did not receive postdilation.

There was no randomized comparator arm in APPOSITION III; instead, investigators used a pooled analysis of recent AMI trials, conducted by the ACTION study group. In that pooled group, MACE at one year was 11.1% and cardiac death was 3.9%, as compared with 9.3% and 2.0%, respectively, in APPOSITION III.

Speaking with heartwire , Montalescot emphasized that this comparison only offers an intriguing glimpse of what this novel stent might offer in AMI. "The only thing we can say is that the overall MACE rate looks good, and the cardiac death rate in APPOSITION III is half of what we see in the recent randomized trials.

"It is a nice new concept. It looks a bit like the old wall stent that we had 15 to 20 years ago, but I don't know any other stent like this one," he said. "It's new technology, and I think, in STEMI, it is very attractive, because you can leave the thrombus behind the stent and know that the stent will adjust as the thrombus resolves."

Dr Cindy Grines

Also commenting on the study to heartwire , Dr Cindy Grines (Detroit Medical Center, MI) said she welcomed another choice in AMI patients. "We've been stuck with these balloon-expandable stents ever since I started putting stents in the coronaries, and a stent like this would help seal the coronary ectasia, the bulging of the artery. And it would really help with sizing, because with AMI patients, if they are vasoconstricted today, they are vasodilated tomorrow."

Grines also pointed to another novel AMI-specific stent, the MGuard (InspireMD) device, a mesh-covered stent designed to trap and exclude thrombus and atheromatous debris.

The Stentys stent already holds CE Mark approval in the EU (APPOSITION III was undertaken as a postmarketing study in Europe). The company is now moving ahead with its FDA-approved pivotal trial, APPOSITION V , in the US, planned to launch in the coming months. That trial will be led by Dr Roxana Mehran (Mount Sinai School of Medicine, New York, NY) and Dr Maurice Buchbinder (San Diego Cardiovascular Associates) and is designed to enroll 880 STEMI patients 2:1 to either the Stentys bare-metal stent or the Abbott Multilink. Primary end point is target vessel failure at 12 months.

Montalescot has previously disclosed receiving grants from Biotronik, Boston Scientific, Brahms, Medtronic, and Stentys. Grines disclosed having no conflicts related to the AMI-specific stents discussed in this story.