Coronary steal due to ruptured right coronary aneurysm causing myocardial infarction in a patient with systemic lupus erythematosus.

A 34-year-old female with a history of systemic lupus erythematosus (SLE) developed an acute inferior myocardial infarction while hospitalized for methicillin-resistant Staphylococcus Aureus sepsis. An emergent coronary angiography revealed an ectatic proximal left coronary artery and a huge aneurysm (37 mm × 32 mm) in the mid-portion of the right coronary artery, which had ruptured into the right atrium. A "steal phenomenon" due to significant left to right shunt resulting from the ruptured aneurysm was the cause of the myocardial infarction. Infection of the wall of the aneurysm might have contributed to the growth and the rupture in the presence of a pre-existing coronary aneurysm.