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 in patients with pulmonary hypertension who are undergoing cardiac catheterization. Cardiac magnetic resonance imaging is useful in these patients to document extrinsic compression, which might otherwise be mistaken for intrinsic atherosclerotic disease.