Dynamic Left Main Occlusion After Aortic Valve Surgery: Recognising Extrinsic Compression by Aortic Root Pseudoaneurysm - A Case Report

Abstract Background Extrinsic compression of the left main coronary artery (LM) by an aortic root pseudoaneurysm is an exceedingly rare but life-threatening cause of acute coronary syndrome (ACS) following aortic valve surgery. Multimodality imaging is essential for diagnosis and surgical planning. Case Summary A 52-year-old male underwent mechanical aortic valve replacement and aortic root reconstruction for infective endocarditis complicated by a 23 mm aortic root abscess. Following initial recovery, he re-presented two months later with persistent chest pain on a background of ten days of intermittent symptoms, with anterior-lateral ischaemic changes on electrocardiography (ECG). Computed tomography (CT) aortography excluded dissection but was not formally reported. In the catheterisation laboratory, fluoroscopy revealed abnormal prosthetic valve rocking consistent with dehiscence. Coronary angiography demonstrated absent antegrade flow in the left anterior descending artery (LAD), impaired flow in the left circumflex artery (LCX), and a pulsatile, systole-predominant LM lesion strongly suggesting extrinsic compression. No percutaneous intervention was performed. Urgent formal CT review confirmed a 5.2 × 4.4 × 4.0 cm left ventricular outflow tract (LVOT) pseudoaneurysm with the LM coursing within its fold and apparent systolic occlusion. Serial ECGs showed gradual improvement, supporting a dynamic mechanism. After multidisciplinary review, the patient underwent successful composite graft replacement and pseudoaneurysm repair at a quaternary centre, with full recovery at four-month follow-up. Discussion This case illustrates three key lessons: the dynamic, systole-predominant angiographic hallmark of extrinsic LM compression distinguishes it from fixed atherosclerotic disease and prevents inappropriate percutaneous intervention; dynamic angiography and CT play complementary roles, and single-phase systolic CT may, in this setting, overestimate the severity of LM occlusion; and early referral to a specialist quaternary surgical centre is essential for definitive repair.