QUANTITATIVE ARTERIOGRAPHY OF APPARENTLY NORMAL CORONARY SEGMENTS WITH NEARBY OR DISTANT DISEASE SUGGESTS PRESENCE OF OCCULT, NONVISUALIZED ATHEROSCLEROSIS

Objectives. The aim of this study was to evaluate, using quantitative arteriography, whether the diameter of visually normal coronary segments might be influenced by the relative proximity of visually apparent disease. Background. Severity of coronary artery lesions is commonly referenced against a presumed normal nearby coronary segment with the presumption that visually smooth segments are relatively free of atherosclerotic disease. Methods. Angiograms from 136 male patients with focal coronary disease were examined, and visually normal segments in the proximal portions of the major vessels were identified for measurement of mean segment diameters. Normal segments with immediately adjacent disease were compared with normal segments with distal disease in the same vessel and compared with normal segments in vessels for which the only other visible disease was in distant vessels. Angiograms with entirely normal findings from 26 age-matched men with atypical chest pain were used as controls. Segments were measured after nitroglycerin administration by means of computer-assisted quantitation. Results. Mean diameters of visually normal segments with distant disease were smaller than those of control segments (p < 0.05). Normal left main and proximal left anterior descending coronary artery segments in patients with disease within the same vessel were significantly smaller than normal segments in patients with distant disease (p < 0.05). Normal segments with immediately adjacent disease had smaller mean diameters than normal segments with distal disease in the same vessel (p < 0.05). Conclusions. Usually normal coronary segments have progressively smaller lumen diameters, depending on the relative proximity of visible disease. Measurement of percent stenosis on the basis of the diameter of apparently normal adjacent reference segments can result in underestimation of coronary lesion severity.