Septic Myocarditis Masquerading as Acute Inferior ST-Elevation Myocardial Infarction

Acute ST-elevation myocardial infarction (STEMI) is a rare and alarming presentation in adolescents, particularly in women. We report the case of a 16-year-old female who presented with classic symptoms of acute myocardial infarction, including severe retrosternal chest pain, ST-segment elevations on ECG, and a significantly elevated troponin I level (18 ng/mL). The ECG showed evidence of ST elevation in inferior leads, suggestive of inferior STEMI. Urgent coronary angiography revealed normal coronary arteries, effectively ruling out coronary occlusion. The diagnostic pivot was guided by concomitant fever, hypotension, profound leukocytosis (40,900/µL), and a markedly elevated procalcitonin level (11.1 ng/mL). Blood cultures were negative. A transthoracic echocardiogram revealed severe global left ventricular dysfunction (35%). Despite negative blood cultures, a diagnosis of septic shock with secondary septic myocarditis was made based on the overwhelming clinical and biomarker evidence. Initiation of antibiotic therapy led to rapid clinical improvement within 72 hours, accompanied by complete resolution of ST-segment elevations. This case underscores septic myocarditis as a critical mimic of STEMI and highlights the importance of a normal angiogram in redirecting management toward life-threatening infectious etiologies.