Background: Pathologic studies have revealed that coronary arteries undergo compensatory enlargement in the presence of atherosclerosis.
Methods: In order to assess coronary artery remodeling in vivo, we used intravascular ultrasound to examine 46 patients (36 men and 10 women; aged 58.2 +/- 6.8 years) with non-calcified plaques. The vessel, lumen, and plaque areas of the atherosclerotic and of normal proximal and distal segments were determined.
Results: A total of 92 atherosclerotic segments were analyzed. The degree of stenosis ranged from 9.2 to 92.8% (mean 34.1 +/- 16.9%) and the plaque area from 2 to 19.6 mm2 (mean 6.3 +/- 3.6 mm2). The vessel area of the atherosclerotic segment (mean 20.4 +/- 7.3 mm2) was larger than that of the proximal segment (mean 18.7 +/- 7.3 mm2, P = 0.018). The vessel area increased in proportion to plaque area. This relationship can be described using the equation y = 23.5(1-e-0.35x). The difference between the vessel area in the atherosclerotic segment and that in the proximal normal segment correlated with the percentage of stenosis (r = 0.53, P < 0.005) until the degree of stenosis exceeded 45%.
Conclusion: This study indicates that coronary artery remodeling, previously observed in pathologic studies, can be evaluated using intravascular ultrasound in vivo. As a result of the compensatory enlargement of the vessel, coronary angiography cannot be used to detect or exclude the early signs of coronary atherosclerosis.