BACKGROUND: Acute ST-segment elevation myocardial infarction (STEMI) due to total occlusion of an unprotected left main coronary artery (LMCA) is rare and often fatal, particularly when complicated by cardiogenic shock.

CASE REPORT: We report the case of a 58-year-old man who presented with sudden, severe chest pain due to an extensive anterolateral STEMI. His condition rapidly deteriorated, with the development of severe hypoxemia, flash pulmonary edema, and cardiogenic shock. Endotracheal intubation was performed, followed by urgent primary percutaneous coronary intervention and initiation of intra-aortic balloon pump support. Coronary angiography revealed a 100% distal LMCA occlusion, which was successfully treated with balloon pre-dilation, aspiration thrombectomy, and drug-eluting stent implantation, restoring TIMI III coronary flow. Despite successful reperfusion, he required escalation to triple vasoactive therapy with norepinephrine, epinephrine, and dobutamine before gradual hemodynamic and respiratory recovery. A notable finding was an anomalous origin of a small circumflex artery arising from the right coronary artery. His course was complicated by delayed sinus node dysfunction, manifested by a brief daytime syncopal episode with a telemetry-documented 7-second sinus pause, necessitating implantation of a dual-chamber pacemaker. He was initiated on guideline-directed medical therapy for heart failure, with improvement in left ventricular ejection fraction from less than 30% at presentation to 40% to 45% prior to discharge.

CONCLUSIONS: This case provides incremental insight into survival after catastrophic total unprotected LMCA occlusion with profound cardiogenic shock, highlighting the role of rapid revascularization and aggressive hemodynamic support, and emphasizing vigilance for delayed post-infarction conduction complications.

Keywords: coronary occlusion, Pacemaker, Artificial, Shock, Cardiogenic