Likelihood of left main coronary artery compression based on pulmonary trunk diameter in patients with pulmonary hypertension

Purpose In patients with pulmonary hypertension, extrinsic compression of the left main coronary artery by a dilated pulmonary trunk may cause angina, left ventricular ischemia, and sudden death. We assessed coronary artery compression in relation to pulmonary trunk diameter and other demographic, echocardiographic, hemodynamic, and scintigraphic variables. Methods Thirty-six patients (aged 15 to 86 years) with pulmonary hypertension, either idiopathic or associated with congenital heart disease, were enrolled. Left main coronary artery compression was defined angiographically as ≥50% obstruction associated with downward displacement of the vessel. Pulmonary trunk and aortic diameters were measured by transthoracic echocardiography. Results Twenty-six patients had angina, of whom 7 had left coronary artery compression. Compression was related to pulmonary trunk diameter (P = 0.002) and to the ratio of pulmonary trunk diameter to aortic diameter (P = 0.02). Compression was not seen at pulmonary artery diameters <40 mm; among 19 patients with values ≥40 mm, the rate was 37%. Similarly, compression did not occur at pulmonary trunk to aortic diameter ratios <1.21; among 27 patients with ratios ≥1.21, the rate was 26%. Conclusion In pulmonary hypertension, noninvasive measurement of pulmonary trunk diameter may be helpful in determining the likelihood of left coronary artery compression and in selecting patients for diagnostic coronary angiography