Complex Coronary Artery Lesions

Excerpt

Contemporary treatment of coronary artery disease is highly dependent on percutaneous coronary intervention (PCI) along with medical management. PCI techniques have advanced significantly over time and are used for stenting even challenging lesions. There are, however, some lesions that present challenges via the conventional PCI route. These complex coronary lesions are categorized based on anatomic, physiological, or functional difficulties.

Some of these complex lesions in coronary vessels include bifurcation lesions, calcified lesions, chronic total occlusions, unprotected left main coronary artery lesions, ostial lesions, and saphenous vein graft stenosis. Each of these lesions presents unique challenges, and the approach to such lesions is individualized. Specialized techniques and cardiologists with advanced skill sets have improved the successful treatment of such occlusions.

Conventional PCI may not adequately treat these lesions, which may require advanced techniques. One such subset of advanced catheter-oriented interventions is complex, high-risk, and indicated PCI (CHIP). These techniques include laser, rotational, laser atherectomy, various bifurcation stenting techniques, and specialized approaches to chronic total occlusions. These techniques are promising; however, studies are inconclusive if they positively impact mortality. Some studies, such as Habib et al, cite CABG as a more effective modality for addressing these lesions.

A brief explanation of some of the most common complex lesions follows.

1. Bifurcation lesions: These arise at or adjacent to the separation of a major coronary artery. They occur when the main coronary arteries divide into two smaller anatomic portions. The three resultant portions are the proximal main branch, distal main branch, and side branch. A bifurcation lesion is one with significant stenosis (> 50%) in a coronary artery involving the origin of a side branch or in a coronary artery adjacent to the origin of the side branch. The Medina classification system assesses and defines the location of stenosis. This system is a simple numeric system that encompasses the main branch, distal branch, and side branch.

2. Calcified lesions: Vascular calcification of the coronary arteries is a common process actively regulated and involves atherosclerotic, inflammatory, and hormonal disease processes. Coronary artery calcification (CAC) involves intimal and medial calcification. CAC increases vessel stiffness and increases the potential for cardiovascular events.

3. Chronic total occlusions: This is the complete obstruction of a coronary artery. These occlusions must show TIMI 0 or TIMI 1 flow and have a duration of at least 3 months.

4. Left main coronary artery (LMCA) disease: Left main coronary artery disease can be problematic given that it is the origin of the majority of the left ventricular coronary supply. An unprotected left main coronary artery leaves the majority of the myocardium susceptible to death if significant stenosis is present. A protected left main coronary artery is such that a bypass graft supplies the left anterior descending artery or the left circumflex artery.

5. Ostial lesion: An ostial lesion starts within 3 mm of the origin of a major coronary artery. These may be challenging to stent due to proximity to the aorta.

6. Stenosis of saphenous vein graft (SVG): Saphenous vein grafts are the most common vessels used in CABG. This type of stenosis occurs commonly, with some reports of up to 20% of patients developing this within one year. PCI of SVG carries a significant risk of myocardial infarction or diminished flow. Atherosclerotic disease within graft results in a high restenosis rate as well.