The Snoopy Sign Behind a MINOCA: Complete Congenital Absence of the Pericardium

Background: Myocardial infarction with non-obstructive coronary arteries (MINOCA) requires further investigation to identify the underlying mechanism. Congenital absence of the pericardium is a rare anomaly, usually asymptomatic and incidentally diagnosed. Case Presentation: A 57-year-old woman presented with prolonged resting chest pain, inferior T-wave inversion, and markedly elevated high-sensitivity cardiac troponin I (4393 ng/L). Transthoracic echocardiography was limited by non-diagnostic standard views and revealed marked cardiac displacement with preserved left ventricular systolic function. Coronary angiography showed unobstructed coronary arteries but raised suspicion of an anomalous right coronary origin. Coronary computed tomography angiography excluded this anomaly and demonstrated complete absence of the pericardium with marked leftward cardiac displacement. Cardiac magnetic resonance confirmed the anatomical diagnosis and showed preserved biventricular systolic function, no late gadolinium enhancement, and diffusely elevated T2 and extracellular volume, consistent with acute non-ischemic myocardial injury. The patient recovered with conservative management and remained asymptomatic at follow-up. Conclusions: Complete congenital absence of the pericardium may be identified during the evaluation of an acute MINOCA-like presentation. Unusual echocardiographic windows, marked cardiac displacement, and difficult coronary engagement should raise suspicion of this anomaly. Multimodality imaging is essential for defining the anatomy, excluding associated coronary abnormalities, and characterizing myocardial injury.