APCU25MPB2 A dangerous blind spot

Introduction Coronary computed tomography angiography (CTCA) is increasingly used as a frontline diagnostic tool for suspected coronary artery disease, owing to its high negative predictive value. However, ostial left main (LM) stenosis remains a recognized blind spot, particularly in patients with recurrent acute coronary syndromes. Missed diagnosis at this critical site may lead to catastrophic outcomes if not identified promptly. We report a case of recurrent unstable angina with initially reassuring CTCA, later revealed to harbor significant ostial LM disease during invasive angiography.Case Presentation A 46-year-old man with uncontrolled diabetes mellitus, hypertension, and dyslipidemia presented with recurrent episodes of typical angina, requiring three admissions for unstable angina. CTCA following his initial presentation demonstrated a calcium score of 0, with only mild proximal LCx and mid RCA disease (CAD-RADS 2). Despite medical therapy, symptoms persisted. On his third admission, invasive coronary angiography revealed critical ostial LM stenosis (70%). Intravascular ultrasound (IVUS) confirmed ostial LM minimal lumen area 5.7 mm 2 with 67% plaque burden. PCI was successfully performed with IVUS-guided stenting of the LM. Post-PCI IVUS demonstrated optimal expansion (MSA 12 mm2, residual plaque burden