Wall Shear Stress and Neointimal Healing Following PCI in Angulated Coronary Vessels

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.

Inclusion criteria

• Patient must be 30 to 80 years old
• Severe coronary lesion in a vessel with ≥ 30-degree angulation requiring percutaneous coronary intervention (PCI)
• Lesion treatable by a single Resolute Integrity or Onyx Abbott Xience Xpedition or Sierra coronary drug-eluting stent.
• Patients with stable ischemic heart disease or acute coronary syndrome undergoing clinically PCI.

Exclusion criteria

• Inability to provide informed consent prior to randomization
• Anatomy requiring coronary artery bypass surgery (CABG)
• History of prior CABG in the territory of the vessel being considered for PCI
• Heavily calcified lesion requiring rotablation or other debulking or scoring device for successful stent deployment
• Large thrombus burden on recent angiography
• Previously stented vessels
• Ostial lesions: lesion located within 5mm of the origin of the left anterior descending artery (LAD), left circumflex artery (LCx), or Right coronary artery (RCA)
• Lesions at bifurcations and those that occlude side branches >2.5mm
• Recent (<72 hours) ST-elevation myocardial infarction (STEMI).
• Planned surgical procedures in the subsequent 12 months
• History of hypersensitivity or contraindication to device materials and their degradants, everolimus, zotarolimus, cobalt, chromium, nickel, platinum, tungsten, acrylic, and fluoropolymers
• History of any solid organ transplantation or subject is on a waiting list for any solid organ transplant
• Left ventricular ejection fraction < 30%
• Known allergies to clinically utilized anti-thrombotic or anti-platelet agents
• Unable to tolerate long term dual antiplatelet therapy
• Pregnancy or lactation