Discussion

The incidence of coronary artery aneurysms has been reported to be 0.2–4.9% of patients undergoing coronary angiography. Aneurysms of the left main coronary artery are even more rare; in a study by Topaz et alReference Topaz, DiSciascio and Cowley³ involving a series of 22,000 coronary angiograms, they were found in only 22 patients (an occurrence rate of 0.1%). Over 50% of the left main coronary artery aneurysms are atherosclerotic in origin. Other aetiologies include congenital malformations, Kawasaki disease, Marfan and Ehlers-Danlos syndromes, Takayasu’s arteritis, syphilitic or infectious arteritis, thoracic trauma, and fibromuscular dysplasia. Isolated left main coronary artery aneurysm without arteriosclerotic lesions is, therefore, rare, and clinical management of these patients is not well established because of the lack of cases documented in the literature.

As with other aneurysms, it appears that thrombosis or embolisation, or both, with vessel occlusionReference Rath, Har-Zahav and Battler⁴ and rupture of the aneurysm with sudden cardiac tamponadeReference Iga, Fujikawa, Ueda, Miki and Konishi⁵ are the two most serious, although rare, consequences and can occur in isolated cases of coronary aneurysm without associated cardiac lesions.

Aneurysms are clinically manifested with acute myocardial infarction accounting for 30–50% of cases.Reference Wang, Ting Ch, Sutton and Cheng^1, Reference Von Rotz, Niederhauser, Straumann, Kurz, Bertel and Turina⁶ The rest either cause myocardial ischaemia or, more often, constitute an occasional finding in coronary angiography. It is reasonable to assume that thrombosis, facilitated by turbulence and local slow flow, can occur within an aneurysm and lead to vessel occlusion, as in our patient the left main coronary artery aneurysm involving the ostial left circumflex artery might have led to inferior wall myocardial infarction.

Although the management of coronary artery aneurysm is not well established as yet owing to the rarity and unpredictable natural history, these dilated sections of the coronary artery are not benign entities because they are subject to spasm, thrombosis, and spontaneous dissection and can be a potential cause of myocardial infarction. In the selected cases of left main coronary artery aneurysm, adequate medical management including anti-platelets and/or anti-coagulation may confer optimal management without surgery with a careful periodic follow-up. If pharmacological treatment fails, then a surgical approach is proposed or an intra-coronary stent implanted. The surgical approach involves the plastic correction of the coronary vessel aneurysm using part of a veinReference Moriyama, Hisatomi, Shimokawa, Taira and Arima⁷ or of an arteryReference Lepojarvi, Salmela, Huikuri and Karkola⁸ or stent implantationReference Leung, Wong, Wu, Tsui, Mok and Lau⁹ or covered stent, plastic correction ligation with bypass graft.