DEFINITION

Coronary artery aneurysm (CAA) is defined as a dilation more than 1.5 times the diameter of adjacent normal segments.¹ It was first described by Morgagni in 1781^2,3; the first case report was published by Bougon in 1812,^1,4 and the first documented case with angiography was published by Munker in 1958.^5,6 Before the advent of coronary angiography, CAAs were detected primarily at postmortem examination; however, most cases today are incidental findings on angiography.

PREVALENCE AND EPIDEMIOLOGY

The reported incidence of CAAs ranges from 0.2% to 4.9% among patients undergoing evaluation for coronary disease.^1,5 They occur predominantly in men at a ratio of almost 3 : 1.⁴ CAAs are predominantly caused by atherosclerosis (52%). They may be single or multiple, may be focal or diffuse, and can involve various segments of the coronary circulation. They most commonly involve the right coronary artery (Fig. 36-1) followed by the left anterior descending (Fig. 36-2) and the left circumflex (Fig. 36-3) arteries.⁴

FIGURE 36-1 A 67-year-old patient with a right coronary artery (RCA) aneurysm presented for preoperative CT angiography evaluation. A, Coronal volume rendered image shows large calcified RCA aneurysm (arrow). B, Oblique sagittal maximum intensity projection better defines the full extent of the aneurysmal dilation (arrow) of the RCA. C, Conventional catheter angiography confirms aneurysmal dilation of the RCA (arrow).

FIGURE 36-2 A and B, Coronary CT angiography shows focal aneurysm (arrows) of the left anterior descending coronary artery. A, Axial image. B, Coronal oblique volume rendered image.

FIGURE 36-3 An 86-year-old woman with shortness of breath. A, Coronary CT angiography shows contrast collection at the level of the mitral annulus (arrow) consistent with aneurysm of the left circumflex coronary artery. B, Oblique maximum intensity projection CT angiography defines aneurysmal dilation of diffusely diseased circumflex artery (arrow).

Atherosclerotic aneurysms of the left main coronary artery are rare, but have been reported.⁷ Other important etiologies include congenital (17%), mycotic-embolic (11%), dissecting (11%), syphilitic (4%), and unclassified (5%).⁴ Although most cases worldwide are secondary to atherosclerosis, systemic inflammatory diseases such as Takayasu arteritis (Fig. 36-4) and the mucocutaneous lymph node syndromes of Kawasaki disease (Fig. 36-5) account for many cases in East Asia.⁸ Modern interventional techniques have also resulted in iatrogenic causes of CAAs. In the current era of percutaneous intervention, CAAs can be seen secondary to balloon angioplasty or stent deployment.⁹ The increasing use of coronary artery bypass grafting techniques has resulted in numerous reports of saphenous vein graft aneurysms (Fig. 36-6), although they remain uncommon.

FIGURE 36-4 A 21-year-old woman with history of Takayasu disease. Axial oblique maximum intensity projection from coronary CT angiography shows aneurysmal dilation of left main coronary artery (arrow).

FIGURE 36-5 An 8-month-old infant with Kawasaki disease. A, Axial maximum intensity projection CT angiography shows aneurysmal dilation of the right coronary artery (arrow). B, Sagittal oblique maximum intensity projection CT angiography confirms aneurysmal right coronary artery (arrow).

FIGURE 36-6 A 76-year-old man presented for postoperative CT angiography assessment of coronary artery bypass graft patency. A, Axial oblique maximum intensity projection image shows a fusiform contrast collection (arrow) adjacent to the ascending aorta. B, Coronal volume rendered image confirms proximal pseudoaneurysm of a saphenous vein graft (arrow).

Although CAAs may be found at any age, atherosclerotic subtypes are predominant later in life, whereas congenital (Figs. 36-7 and 36-8), mycotic-embolic, and dissecting types are found in younger age groups. Multiple CAAs in childhood and adolescence are usually late complications of Kawasaki disease (Fig. 36-9).¹⁰

FIGURE 36-7 A 17-year-old patient with Down syndrome and uncorrected endocardial cushion defect. Axial maximum intensity projection CT shows diffuse coronary artery ectasia of the left coronary artery (arrows).