Abstract Body (Do not enter title and authors here): Background: While ventricular fibrillation commonly occurs during acute myocardial infarction, need for multiple successive defibrillations (>20) during PCI is exceedingly rare and represents significant clinical challenge with no established management protocols.

Methods: A retrospective analysis examining VF waveform morphologies, defibrillation thresholds, hemodynamic parameters, quantitative coronary angiography, and post-PCI perfusion status.

Results: A 58-year-old male with hypertension, tobacco and marijuana use presented to the emergencydepartment with four days of bilateral arm pain following snow shoveling. Initial vital signs were stable, but while awaiting evaluation, he suffered a sudden ventricular fibrillation arrest. ACLS was initiated immediately with an unprecedented series of 28 defibrillations (6 during initial resuscitation, 22 during cardiac catheterization) required for recurrent ventricular fibrillation. ROSC was achieved after 22 minutes of cardiopulmonary resuscitation. Post-arrest ECG demonstrated ST-segment elevations in leads II, III, aVF, and V3 with T-wave inversions in lateral leads. Laboratory studies revealed marked troponin elevation (initial 45 ng/mL, peaking at 10,000 ng/mL), leukocytosis (21,000/μL), elevated lactate (7.4 mmol/L), and transaminitis (AST/ALT 647/336 U/L). Emergency coronary angiography revealed 100% occlusion of the proximal right coronary artery and 50% stenosis of the mid-left anterior descending artery. Despite successful percutaneous coronary intervention with a 4.0×22mm drug-eluting stent to the proximal RCA achieving TIMI-3 flow, the patient experienced incessant ventricular fibrillation throughout the procedure. Cardiogenic shock developed with cardiac index of 1.9 L/min/m2, requiring norepinephrine infusion and intra-aortic balloon pump support. Targeted temperature management at 33.3C was initiated but discontinued when purposeful movements were observed. Echocardiography demonstrated mid inferoseptal, mid inferior, and apical septal hypokinesis with preserved ejection fraction of 45%. The patient was successfully extubated on day 3 with intact neurological function.

Conclusion: This case introduces the concept of "reperfusion-triggered electrical storm" in delayed-presentation STEMI, where prolonged ischemia creates a uniquely arrhythmogenic substrate requiring an extraordinary number of defibrillations.