Generation of a giant coronary artery aneurysm from an intra-plaque cavity with a ruptured fibrous cap: an observation over time through coronary angiography.

A 74-year-old man underwent coronary artery bypass graft surgery. Thirteen years later, he presented with complaints of exertional anterior chest oppression again. Computed tomography coronary angiography revealed the significant stenosis at the mid right coronary artery (RCA). In addition, a giant proximal left anterior descending (LAD) coronary artery aneurysm (CAA) was found. We did not observe this aneurysm on his previous coronary angiogram, performed 12 years previously (i.e., 1 year after his surgery). Diagnostic coronary angiography confirmed the computed tomography findings. We found the significant stenosis at the mid RCA site and a giant proximal LAD coronary artery aneurysm. First, we performed the percutaneous coronary intervention (PCI) at the mid RCA significant stenosis. We implanted the drug eluting stent. After that, we performed PCI to treat the giant proximal LAD coronary artery aneurysm with a covered stent (a 2.8/26-mm polytetrafluoroethylene covered stent), and complete exclusion of the aneurysm was obtained. The etiology of this patient's aneurysm was unclear, but we speculate that the mechanism responsible for the appearance of this aneurysm was the expansion of the intra-plaque cavity with the ruptured fibrous cap. This observation over time through coronary angiography suggests that giant CAAs might be generated asymptomatically under certain conditions. In this case, the possible conditions might have been the chronic total occlusion of the mid-LAD and the significant stenosis just distal to this aneurysm, so increasing flow and pressure against this diseased cavity might have caused this giant CAA to form. In addition, another speculation might have been the local inflammation or macrophage-based degradation after coronary artery bypass graft surgery.