Aneurysms of the left main coronary artery are very rare. 1 We report on a patient with critical stenosis and large aneurysm of the ]eft main coronary artery, critical three-vessel disease, and an aberrant conus artery without significant atherosclerotic changes rising from the right coronary ostium. A 59-year-old man with a 2-year history of stable angina pectoris was hospitalized with signs of anterolateral ischemia in the electrocardiogram and retrosternal pain that was unresponsive to nitroglycerin. There was no patient or family history of connective-tissue or infectious disease (endocarditis or mucocutaneous syndrome). Under standard therapy the pain was relieved, the electrocardiographic changes regressed, and creatine kinase (including MB fraction), aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase levels remained normal. Total cholesterol was 5 mmol/L (<5.2), high-density lipoprotein fraction 1 mmol/L, and triglycerides 3.8 mmol/L (normal <2.1). Because the patient had signs ofischemia on admission even though he was not taking chronic antianginal medication, he was given a cautious exercise test after administration of a p-blocker, a nitrate, and a platelet inhibitor to document ischemia and/or symptoms under therapy and thus the indication for catheterization. Left main or three-vessel disease was suspected because of early-onset angina pectoris, downsloping ST segment depression of up to 3.1 mm, and lack of increased blood pressure on exertion. The exercise test was immediately interrupted. At cardiac catheterization, left ventricular ejection fraction was 47%, with inferior akinesis and anterolateral hypokinesis. The abdominal and thoracic aorta showed severe diffuse atherosclerotic changes and moderate dilatation. The left main coronary artery showed critical stenosis and a huge fusiform aneurysm (Fig. 1, A), with proximal occlusion of the left anterior descending artery and critical stenosis and ectasia of the left circumflex coronary artery (Fig. 1, B). The right coronary artery showed severe diffuse atherosclerotic changes, with saccular aneurysms and critical stenoses of its proximal part and of the posterior descending and posterolateral branches (Fig. 1, C). A conus branch (Fig. 2) went off separately from the right coronary ostium and gave collaterals to the left anterior descending artery. This isolated conus branch showed kinking but no aneurysm formation or signifiCant stenosis. No significant dampening or ventricularization of the pressure waveform occurred during cannulation of the left main coronary. All laboratory parameters were normal, including blood count, electrolytes, creatinine, C-reactive protein, blood sedimentation rate, anti-DNA, antinuclear antibodies, antineutrophil cytoplasm antibody, viral and bacterial serologic (including Venereal Disease Research Laboratory). The chest x-ray, abdominal ultrasound, and lung function test results were normal. The patient underwent uneventful coronary artery bypass surgery (mammary artery graft to the left anterior descending artery, vein grafts to the left posterolateral artery on the right posterior descending artery and the right ventricular branches). With no clues in the patient's history or laboratory findings suggesting active vasculitis and endocarditis as the underlying disease, an atherosclerotic cause of the aneurysms seems most probable. Kawasaki disease and a burned out vasculitis are improbable, but cannot be completely excluded. This case presents three unusual features. First, although coronary artery aneurysms or ectasia are fairly common,2, 3 left main aneurysms are very rare. 1, 4 Defined as permanent luminal enlargement of the left main coronary artery greater than two times the diameter of the patient's largest coronary vessel or three times the diameter of a standard coronary catheter, aneurysms can be classified as saccular or fusiform. 1 Pseudo filling defects, either from true thrombus formation or, more commonly, swirling of contrast material in the aneurysmal structure leading to admixture with blood and dilution, can lead to poor lumen definition and misinterpretation of severity ofstenosis. Pseudo filling defects can be avoided by prolonged and forceful injection that adequately fills tile aneurysm and coronary artery. 1 The second unus'ual feature about this case is the aberrant conus branch rising from the right coronary ostium. The abnormal origin of the conus branch was recognized some time ago, 5 as was its importance as a collateral flow pathway in patients with total obstruction of the left anterior descending artery. ~ Third, this conus branch was the only coronary artery spared from significant atherosclerotic disease: because of the critical stenosis of all three coronary arteries and the main stem, it is possible that the patient owed survival to this aberrant conus branch, which efficiently collateralized the left anterior descending artery.
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Dec 15, 1996
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