Extrinsic compression of the left main coronary artery by the pulmonary artery in patients with long-standing pulmonary hypertension

Left main coronary artery compression by the pulmonary artery may be seen i n patients with pulmonary hypertension who are undergoing cardiac catheteri zation. Cardiac magnetic resonance imaging is useful in these patients to d ocument extrinsic compression, which might otherwise be mistaken for intrin sic atherosclerotic disease.