Postdilation May Improve Outcomes After Self-Expanding Stent Is Used in Primary PCI
In patients undergoing primary PCI, the use of self-expanding stents results in acceptable rates of MACE at 1 year, but events are even fewer when postdilation is used, according to the APPOSITION III registry study published online February 17, 2015, ahead of print in EuroIntervention.
The results were first presented at the American College of Cardiology/i2 Scientific Session in March 2013.
Karel T. Koch, MD, PhD, of the University of Amsterdam (Amsterdam, the Netherlands), and colleagues looked at 1-year outcomes in 965 STEMI patients (mean age 60 years; 77% male) undergoing primary PCI with either the bare-metal (n = 717) or paclitaxel-eluting (n = 248) version of the self-expanding nitinol Stentys stent (Stentys; Paris, France) between April 2010 and January 2012. The study involved 51 sites in 14 European countries, with the choice of BMS or DES left to operator discretion.
At 1 year, the rate of MACE (cardiac death, recurrent target-vessel MI, or clinically driven TLR; primary endpoint) was 9.3%, with cardiac death reported in 2.0%, target-vessel MI in 1.3%, and clinically indicated TLR in 7.4%. The rate of definite/probable stent thrombosis was 3.5% (definite, 2.8%).
Postdilation Changes Outcomes Substantially
Postdilation was performed in 60% of the first 400 patients and—after a recommendation by the steering committee—in 77% of the subsequent 565 patients. In an interim safety analysis at 1 year, there were trends toward lower rates of MACE, cardiac death, and clinically indicated TLR and clear advantages in recurrent target-vessel MI and definite stent thrombosis in those who received postdilation (table 1).
Landmark analyses demonstrated the early emergence of a benefit for postdilation, with the MACE rate at 30 days more than halved for postdilation (2.7% vs 5.6%; P = .02). The same trend was seen for the individual components of MACE and for definite stent thrombosis within 30 days. However, clinical outcomes were similar between the groups between 30 days and 1 year.
There were no differences between patients treated with DES and BMS for 1-year MACE (10.7% vs 8.8%, respectively; P = .42) or any other endpoints.
Research Needed to Show Superiority of DES Version
According to the study authors, the stent was developed to overcome problems with malapposition, which tends to occur more frequently after primary PCI compared with elective procedures. The presence of thrombus may result in unintentional stent undersizing.
Due to the stent’s self-expanding features, it adapts to the vessel wall and is thought to accommodate changes in coronary anatomy immediately after the index event. According to Dr. Koch and colleagues, it was designed to keep chronic outward force low so as to prevent chronic vessel wall injury and subsequent increase of neointimal hyperplasia—problems seen with first-generation self-expanding stents.
“As a consequence, the self-expanding force of the device alone is probably not sufficient to treat a stenotic lesion, preventing adequate stent expansion when postdilation is not performed,” they write. “However, the resistive outward force against vessel compression is high, allowing low residual stenosis after balloon postdilation.”
The authors say the lack of differences in clinical outcomes between the bare-metal and the paclitaxel-eluting versions of the stent “might be explained by patient selection, due to the nonrandomized nature of this comparison, the play of chance (small sample in the DES group), and/or a true lack of efficacy due to an unfavorable interplay between drug, polymer, and tissue.”
However, they say, future studies with the DES version “are needed to confirm a superior efficacy with DES versus BMS, as has been shown with balloon-expandable stents.” Additionally, the authors write, randomized trials comparing STENTYS with second- or third-generation DES are needed before its use can be accepted as the standard of care. A sirolimus-eluting version of the stent has been developed and is under clinical investigation, they add.
Koch KT, Grundeken MJ, Vos NS, et al. One-year clinical outcomes of the STENTYS Self-Apposing coronary stent in patients presenting with ST-segment elevation myocardial infarction: results from the APPOSITION III registry. EuroIntervention. 2015;Epub ahead of print.
- The APPOSITION III study was funded by STENTYS.
- Dr. Koch reports receiving institutional research grants from STENTYS.