Abstract Body: Case Presentation
A 55-year-old male with a past medical history of hypertension, aortitis, focal seizures, migraines, and tobacco use presented with chest pain and shortness of breath. He became unresponsive at home, prompting ED evaluation. Initial ECG was unremarkable with no ischemic changes. Troponins peaked at 100 ng/L. A transthoracic echocardiogram showed a normal left ventricular ejection fraction (LVEF) of 60–65% with no wall motion abnormalities. Elective cardiac catheterization was pursued to evaluate for coronary artery disease.

Differential Diagnosis
Acute coronary syndrome (ACS), stroke, transient ischemic attack, seizure, GERD, and anxiety were considered. The normal ECG and preserved ejection fraction initially lowered suspicion for ACS, though rising troponins remained concerning.

Treatment and Management
Coronary angiography revealed severe multivessel disease including diffuse left main coronary artery (LMCA) stenosis. Midway through the procedure, the patient developed chest pain and cardiac arrest due to pulseless electrical activity and received 25 minutes of cardiopulmonary resuscitation (CPR) before acheiving return of spontaneous circulation (ROSC). Emergent veno-arterial extracorporeal membrane oxygenation (VA-ECMO) was initiated. A non-selective aortic root angiogram showed 100% LMCA occlusion and the patient underwent salvage percutaneous coronary intervention (PCI) to the LMCA. A micro-axial pump was placed. He underwent rescue three-vessel coronary artery bypass grafting (CABG) after stabilization.

Outcome and Follow-Up
Despite aggressive intervention, the patient’s LVEF dropped to 14% with persistent cardiogenic shock. Serial echocardiograms showed no improvement. He was transitioned to comfort care and passed away 10 days after admission.

Teaching Points
Total LMCA occlusion is a rare but catastrophic event, especially when iatrogenically precipitated during elective procedures. Non-invasive cardiac imaging (e.g., coronary CTA, calcium scoring) may help stratify risk before elective catheterization in patients with significant risk factors prior to initiating invasive procedures. Early recognition, effective CPR, mechanical circulatory support including ECMO and micro-axial pumps, and coordinated multi-disciplinary revascularization strategies are critical in such high-risk presentations.