A55-year-old man with previous percutaneous coronary intervention for STEMI, vertebrobasilar infarction, and recent thoracic endovascular aortic repair (TEVAR) for a descending thoracic aortic aneurysm presented to the emergency department with acute chest and back pain without any trauma. He also had hypertension, diabetes, hyperlipidemia, and routinely take the medication. On arrival, his vital signs showed a markedly elevated blood pressure of 178/120 mmHg, while the others within normal limit.

EKG showed no new ischemic changes. Laboratory result revealed mildly elevated inflammatory markers and NT-proBNP, with normal troponin. CT angiography identified a 5.9×6.5 cm giant RCA aneurysm with thrombus, total mid-distal RCA occlusion, a fistula to the right atrium, and also probable acute pulmonary embolism involving the segmental branch of the right lower lobe.

The coronary angiography showed a giant right coronary artery (RCA) aneurysm with total occlusion at mid-RCA and collateral flow from the left circumflex artery. It is different with right coronary angiography at 4 years ago that showed no coronary aneurysm. The left coronary artery has a good flow to the distal without any significant stenosis and patent stent on 1st diagonal artery branch.

After discussing with the heart team, the surgery was planned. After several days of patient's condition improvement, the surgical was performed. Surgical exploration was undertaken via median sternotomy. Intraoperative findings included a giant RCA aneurysm measuring approximately 6 cm with massive intramural haematoma, a fistulous connection to the RA, and a proximally visible RCA orifice with distal total occlusion. The aneurysmal sac was resected, the RA wall was repaired, and a coronary artery bypass graft (CABG) was performed using a reversed saphenous vein graft from the proximal RCA to the distal RCA segment. Echocardiography on 4^th day postoperative day (POD 4) showed preserved biventricular function without residual mass. Coronary CT angiography on POD 7 confirmed patent RCA graft and resolution of the aneurysmal mass.

This case exemplifies the importance of early surgical referral in patients with symptomatic giant coronary aneurysms, especially when complicated by fistulous drainage or thromboembolic phenomena. Furthermore, it underscores the value of a multidisciplinary approach in the diagnosis and perioperative management of such complex cardiovascular cases.