Clinical findings:
(1) The patient has a history of severe pulmonary hypertension with an enlarged pulmonary artery trunk.
(2) The patient has angina and/or signs of myocardial ischemia and/or sudden collapse.
(3) An ECG taken during an episode shows ischemic changes.
(4) The symptoms improve after therapy with epinephrine or theophylline but not after therapy with nitroglycerin.
(4) Coronary angiography does not show a level of coronary arterial occlusion that is able to explain the clinical findings. It may show downward displacement of the left main coronary artery and/or an extrinsic narrowing.
The findings occur when the distended pulmonary artery compresses the left main coronary artery.
Risk factors for left main coronary artery compression (Mesquita et al):
(1) ratio of pulmonary artery trunk to aorta diameters >= 1.21 (rate 26%)
(2) pulmonary artery diameter >= 40 mm (rate 37%)
The compression can be detected using CT coronary angiography.
Management may involve:
(1) reduction of pulmonary artery pressures
(2) placement of an endovascular stent into the left main coronary artery.
