A 60-year-old man was diagnosed with non–ST-segment elevation acute coronary syndrome (ACS) (Figure A). Coronary angiography (CAG) showed collateral flow from the left to right coronary artery (RCA) without occlusion (Figure B, C). Intravascular ultrasound (IVUS) revealed plaque-rich stenosis (Figure D), treated with drug-eluting stent (DES) placement.One month later, he was brought to our hospital due to ventricular fibrillation, requiring Veno-arterial extracorporeal membrane oxygenation (VA-ECMO). CAG showed mid-RCA stenosis refractory to 1 mg intracoronary isosorbide dinitrate (ISDN) (Figure E). OCT demonstrated fibrous cap disruption in the mid RCA, with otherwise normal adjacent segments. (Figure F-H). Although definitive plaque rupture was not evident, the lesion was considered potentially responsible for ACS, and PCI with DES implantation was performed. Continuous intravenous ISDN was administered post-PCI. After neurological recovery under targeted temperature management (TTM), VA-ECMO was weaned on day 3, with no significant ECG changes during TTM.Three hours later, ST elevation (Figure I, J) and pulseless electrical activity required VA-ECMO reinstitution. CAG showed distal RCA occlusion relieved after 15 mg ISDN (Figure K, L). OCT revealed microthrombus, multiple intimal injuries, and vessel shrinkage (Figure M–P). He died on day 4 from non-occlusive mesenteric ischemia despite intensive care.This patient experienced three ACS episodes in a short period, two at rest in the early morning. In the first event, the collateral flow suggests transient occlusion, possibly due to resolved thrombus or severe spasm. Intimal rupture has been documented in vasospastic angina; however, the extensive and multiple lesions identified in our case on final-event OCT may represent a more severe phenotype that has not been well characterized in previous literature.1 These findings underscore the potential of spasm to trigger cardiac arrest and the diagnostic utility of OCT.Figure Legends(A) Initial ECG. (B) Stenosis. (C) Collateral flow. (D) Plaque-rich stenosis. (E) Mid-stenosis. (F) Fibrous cap rupture. (G, H) Normal segments. (I, J) ECGs around recurrent arrest. (K) Occlusion. (L) Restored flow. (M, arrow) Thrombus. (N–P, arrow) Intimal injuries and vessel shrinkage.