Giant Left Main Coronary Artery Aneurysm Presenting as Multiple Implantable Cardioverter Defibrillator Shocks

Giant aneurysms of the left main coronary artery are one of the rarest findings in cardiology, encountered in less than 0.02% of patients. The presentation is usually the same as coronary artery disease since most coronary aneurysms in the western world are associated with atherosclerosis. Here we report the first case of giant aneurysm of the left main coronary artery presenting as ventricular tachycardia with multiple shocks of the defibrillator in a 57-year-old man with heart failure. We also review the etiology, pathology, and management of coronary aneurysms.


Introduction
Coronary artery aneurysms (CAAs) are very rare clinical entities; among them giant left main coronary artery aneurysms (LMCAAs) are exceedingly rare, encountered in less than 0.02% of patients [1]. Etiology of CAA varies depending on age, comorbidities and even geographical area. The etiology usually determines presentation and management. Herein we report a unique case of giant LMCAA in a 57-year-old man with heart failure with reduced ejection fraction (HFrEF), who presented to our emergency department with chest pain after his implantable cardioverter defibrillator (ICD) fired 12 times. Urgent diagnostic catheterization showed giant LMCAA without signs of coronary artery disease (CAD). The patient was started on dual antiplatelet therapy. He remained asymptomatic for more than a year. We also review current literature on various diagnostic modalities and different management approaches of CAAs.

Case Presentation
A 57-year-old man with hypertension, diabetes, obesity, and HFrEF presented with chest pain, palpitations, and syncope the day before. His ICD fired 12 times. His vitals were unremarkable. Physical examination was significant for irregular pulse. EKG showed normal sinus rhythm with frequent premature ventricular complexes and left anterior fascicular block ( Figure 1).  Urgent cardiac catheterization showed no evidence of occlusive CAD. There was however a large saccular LMCAA involving the ostium of the left anterior descending (LAD), left circumflex (LCX), and ramus intermedius arteries. The size of the aneurysm was measured to be 37.4 mm x 20 mm ( Figure 2, Video 2). Autoimmune workup was negative ( Table 1). The patient was started on dual antiplatelet therapy with aspirin and clopidogrel. CT surgery evaluated the patient, but did not recommend intervention. The patient had successful implantation of a cardioverter defibrillator during the same admission. He was seen in ED one year later with suspicion for pulmonary embolism. CT chest angiogram showed LMCAA to be 1.5 cm in diameter ( Figure 3). Two months after the ED visit, he was seen in the clinic symptom free and ICD was functioning well.

Discussion
CAA is a segment of the artery with width greater than length and diameter greater than diameter of a normal adjacent segment or 1.5 times larger than the largest coronary vessel ( Figure 4)   The etiology of CAA varies depending on age and geographical area. Atherosclerosis is responsible for half of CAAs in the West, followed by congenital (17%) and infectious (10%) aneurysms. Kawasaki disease is the dominant cause of CAA in Japan [3]. Inflammatory disorders and connective tissue diseases are usually associated with ectasias and are more frequent in younger patients [3]. Iatrogenic causes include trauma from balloon inflation pressure, intervention in acute myocardial infarction, use of nonsteroidal anti-inflammatory drugs, steroids, and colchicine, which can cause improper healing. Cocaine causes severe hypertension and vasoconstriction, thus damaging the endothelium and promoting CAA formation [6].
CAAs in CAD are thought to be caused by turbulent blood flow damaging the wall [3]. However, there must be other factors because most patients with CAD do not develop CAA.
Usually patients are asymptomatic and most CAAs are found incidentally. Presentation depends on the etiology and/or complications. Complications of CAA include embolization, rupture, fistula formation, tamponade, hemopericardium, dissection, vasospasm, and vessel compression [2,3].
Coronary angiography remains the best method to identify CAA [2]. It provides information about location, size, and shape of CAA, but it only sees the vessel lumen. Thus, the true size of CAA could be underestimated, or CAA can be missed if thrombus occludes it [4]. Intravascular ultrasound corrects these limitations, providing transmural images and information about wall structure and luminal composition [4,7]. CT coronary angiography provides fast information about CAA's location, shape, size, and wall composition, but no treatment option. CT angiography is useful in following patients with known CAAs [4].
Management of CAA depends on presentation, etiology, size, location, associated infection, and extent of atherosclerosis [4]. In adults with CAD, medical reduction of cardiovascular risk factors should be started. Long-term antiplatelets and potentially anticoagulation should be started since thrombosis and/or embolism are of concern [8]. Percutaneous intervention with stent placement can be done in aneurysm with diameter up to 10 mm [9]. Surgery is indicated in patients, who are not candidates for percutaneous intervention, obstructive CAD, and large saccular aneurysms at risk for rupture [4,10].
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