Polytetrafluoroethylene covered stents during PCI: Wanting more from our “savior”

Abstract

The polytetrafluoroethylene (PTFE) covered stents (PCS) are an essential part of the “life-saving tool kit” in almost every Cath Lab across the world. Developed in the late 1990s (Jostent Coronary Stent Graft, Jomed GmbH) for the treatment of rare but potentially catastrophic complication of coronary artery perforations (CAP) and for safe and effective treatment of coronary artery aneurysm (CAA), it was also hypothesized that this device with a sandwiched PTFE layer between two layers of bare-metal stent (BMS) may also act as a barrier and prevent InStent Restenosis (ISR) or distal embolization during PCI of ulcerated and thrombotic lesion. However, subsequent studies demonstrated worse intermediate term outcomes for PCS compared to BMS related to higher rates of target vessel failure, ISR, and stent thrombosis (ST). CAP occurs in less than 0.5% cases of PCI and apart from distal wire perforations, the majority still occur in larger vessels during stent implantation or post dilation. Severe perforation (Ellis type III) with free flow of blood into pericardium has a very high mortality unless salvaged rapidly and effectively by sealing up the tear in the artery in the Cath Lab. So, PCS avoids emergency surgery and saves lives. The PCS (GraftMaster, Abbott Vascular) has been revisited in this issue of journal by Parikh et al who have retrospectively reviewed their experience and long-term outcomes (up to 10 years) of the use of this device for both CAP and CAA over a 15-year time frame from 2003 to 2017. Although the numbers are small (and thankfully they should be!), they do add to our knowledge. As regard to CAP, it occurred in 67 out of 21,149 patients (0.3%) of the PCI and only a third of this (24 patients) required PCS, a median of 1 PCS per patient to seal the perforation. Ten of these patients had cardiac tamponade, pericardial drain was needed in seven, only one patient required emergency surgery, and two (8%) died during the hospital admission. At follow-up, the outcomes were favorable with low rates of TLR (of 2.6% at 3 years and 17.8% at 5 years). There was no PCS thrombosis and ISR occurred in 25% over the entire duration of follow, a median of 55 months. In the patients, who underwent elective PCS for CAA (eight patients), there were no death, no ISR, and no TLR at a median follow-up of 49 months. Previous studies of PCS use for CAP have demonstrated less favorable long-term outcomes. Kawamoto et al reviewed their data over a similar 11-year time frame with a 1.3% CAP (285 patients). Fifty-seven patients were treated with 72 PCS, and 7% died in hospital. In an elegant landmark analysis beyond 30 days, they demonstrate TVR of 17% and 26% at 1 and 3 years, respectively, and ST at 2% and 5% at 1 and 2 years, respectively, despite continued dual antiplatelet therapy. Despite being our “savior,” the design of PCS remains unchanged for the last 20 years and has a number of limitations; it is a large profile thick strut, rigid, and difficult to deliver BMS. It has high restenosis rate (up to 30%) as well increased thrombosis rates related to its thick struts and delayed endothelialization over the PTFE. A number of procedural and technical considerations could improve the intermediate term outcomes of PCS. First, the PCS being two layeredmetal stent needs to be implanted at high pressures (nominal 15–16 atm) and then post dilated with a noncompliant balloon to 18–20 atm. If CAP is not adequately sealed, then an increase of noncompliant balloon size to 1:1.1 may be needed. This not just achieves adequate sealing of the perforation but also achieves maximal luminal gain to help decrease ST and restenosis at follow-up keeping Received: 17 September 2019 Accepted: 17 September 2019