PCSK9 and coronary aneurysm: Although the mechanism by which this coronary aneurysm shrinks is multifactorial and difficult to pinpoint definitively, it is thought to reflect thrombus formation within the aneurysm due to blood flow diversion caused by bypass surgery, combined with the reduction in vascular inflammation, improvement in endothelial function, and plaque stabilization achieved by introducing PCSK9 inhibitors.