Acute inferior ST-elevation myocardial infarction (STEMI) alone contributes to approximately 10% of in-hospital mortality due to ischemic heart disease. Right ventricular involvement occurs in 50% of patients who present with inferior STEMIs, increasing in-hospital mortality to 31%. In the setting of concomitant severe tricuspid regurgitation, acute rupture of the papillary muscles within the right ventricle should be considered in the differential diagnosis. The authors present the case of a patient with intractable hypoxia in the setting of an acute inferior STEMI complicated by rupture of the posterior tricuspid valve papillary muscle.