Aorto-ostial lesions (AOL), located at the origin of the right and left coronary arteries and surgical bypass grafts, are of critical clinical importance. These lesions compromise blood supply to large myocardial territories and can cause extensive myocardial ischemia. The purpose of this chapter is to review unique lesion, anatomic, and procedural characteristics that contribute to these challenges and to address novel approaches designed to facilitate the treatment of these lesions.

Flow-limiting AOLs are defined as stenoses located within 3 mm of the origin of the native coronary arteries and of surgical bypass grafts.¹ The challenge of percutaneous coronary interventions (PCI) in AOL is derived from their anatomic location and variable relationship with the aorta. Percutaneous interventions in AOL may result in inferior procedural and clinical outcomes compared to interventions in non-AOL coronary lesions.² Optimal outcome requires complete stent expansion and apposition to the vessel wall, complete lesion coverage with the stent, and accurate localization of the proximal stent edge within a virtual aorto-ostial landing zone (AOLZ)³ (Figure 19A-1). Inferior outcomes may be due to inaccurate stent deployment (geographic miss) as well as to unique anatomic and histologic characteristics of AOL that may increase the risk of restenosis and stent thrombosis. Factors that challenge optimal AOL stenting are summarized in Table 19A-1.

The origin of the native coronary arteries from the aorta has a unique 3-dimensional funnel-shaped anatomy, transitioning to a tubular geometry further downstream⁴ (Figure 19A-2). Additionally, the coronary arteries may have variable vertical and horizontal takeoff angles relative to the plane of the aortic wall. Coronary stents have a cylindrical design, and apposition to the wall of the funnel-shaped ostium may not be achieved (Figure 19A-3A). An acutely angulated takeoff angle of the coronary arteries relative to the aortic wall makes it challenging to deploy the whole circumference of the proximal edge of the stent within the AOLZ (Figure 19A-3B).

Ostial lesions frequently have abundant fibrous tissue and excessive calcification.⁵ These lesions may be difficult to expand with a balloon (Figure 19A-4) and may require use of specialized techniques such as cutting balloons, scoring balloons, and rotational atherectomy. Incomplete stent expansion may occur despite extensive lesion preparation.

A high index of suspicion for the presence of AOL is required when performing coronary angiography. Both proximal nonselective contrast injection within the aorta and injection via a catheter deeply intubated within the vessel with its tip located distal to the AOL may fail to demonstrate the ostial stenosis. Wedging of the pressure tracing may alert the operator to the presence of a flow-limiting AOL (Figure 19A-5). Ostial lesions may be eccentric and asymmetrical and may therefore only be visible angiographically in certain projections. Intravascular imaging (intravascular ultrasound and optical coherence tomography) may be especially useful in confirming the diagnosis of AOL (Figure 19A-6). During PCI, it is advisable to use nonaggressive guide catheters to avoid ostial trauma (eg, JL 3.0-3.5 and JR 3.0-3.5 for the left and right coronary arteries, respectively). To compensate for the minimal support provided by these catheters, an extra-support coronary guidewire may be used. Percutaneous treatment of ostial chronic total occlusions may be especially challenging because of the difficulty in identifying the vessel lumen and in seating the guide catheter in a stable position upon the aortic wall. Such cases may benefit from contralateral contrast injection into a different coronary artery that supplies the distal segment of the occluded vessel via collaterals, in order to identify the occluded lumen and guide antegrade wiring (Figure 19A-7). Alternatively, such cases should be considered for treatment with the retrograde wiring technique.