Evaluation of WSS and Neointimal Healing Following Percutaneous Coronary Intervention of Angulated Vessels With Resolute® Integrity Zotarolimus Eluting Coronary Stent Compared to XIENCE Xpedition® Everolimus Eluting Coronary Stent

The past two decades have registered major advances in cardiovascular medicine that have improved patients' survival and quality of life. One area of major research and innovation is the field of percutaneous coronary interventions (PCI), a non-surgical procedure used to treat a narrowed heart artery with stents. Stents are metallic tubular supports placed inside a blood vessel to relieve an obstruction and restore blood flow to the heart muscle. Stents could also be coated with a drug (drug-eluting stents - DES) that improves local healing and inhibits growth of scar tissue (smooth muscle and fibrous cells) within the vessel that otherwise could lead to re-narrowing.

The investigators study will evaluate two FDA-approved DES, currently in use, with respect to coronary vessel healing and long term patency. These include the XIENCE Xpedition Everolimus drug-eluting stent (X-EES) from Abbott Vascular and Resolute Integrity® Zotarolimus drug-eluting stent (R-ZES) from Medtronic, Inc, both of which have been shown in large clinical trials to be safe and effective. This study will evaluate the effects of apparently subtle differences in stent design between these two platforms that may have important effects on regional plaque response and blood flow dynamics immediately after stent deployment and stent healing and scar formation at 12 months follow up.

Several aspect of the R-ZES compared to the X-EES design may result in more favorable regional plaque response and blood flow dynamics immediately after stent deployment. These include a more compliant stent design made of a single sinusoidal wire with no connector between struts that is likely to be more comformable to a curved or angulated coronary vessels. In heart vessels which are not angulated, these features may not make a major difference in outcomes as studies already suggest. Whereas, in narrowed arteries which are curved or angulated, the use of X-EES could result in more straightening of the vessel's natural curvature and more disturbance in flow patterns. In contrast, the use of R-ZES in angulated arteries could cause less hemodynamic disturbances. There is a great deal of data suggesting that disturbances in local blood flow patterns and creation of eddy currents ('turbulent' blood flow) could adversely affect stent healing and exacerbate neointimal tissue growth.

Using two intravascular imaging technologies, the optical coherence tomography (OCT) and intravascular ultrasound (IVUS), this study aims to investigate differences in scar tissue coverage within the stented region and the degree of narrowing at the edges of the stent in patients undergoing clinically-indicated PCI (with R-ZES and X-EES) at 12-month follow-up.