Contribution of inadequate compensatory enlargement to development of human coronary artery stenosis: An in vivo intravascular ultrasound study

OBJECTIVES: This intravascular ultrasound study sought to examine to what extent native coronary artery stenosis is accompanied by vessel wall thickening or inadequate compensatory enlargement (relative vessel constriction), or both. BACKGROUND: In human femoral arteries, inadequate compensatory enlargement is reported to be a paradoxic mechanism for the development of severe arterial lumen narrowing. However, it is unclear in human coronary arteries whether inadequate compensatory enlargement contributes to the development of critical arterial stenosis. METHODS: Thirty-five primary coronary artery lesions from 30 patients (19 men, 11 women; mean +/- SD age 65 +/- 13 years) were imaged by intravascular ultrasound. The vessel cross-sectional area and lumen area were measured, and the wall area (vessel cross-sectional area minus lumen area) was calculated at the lesion site and at the proximal and distal reference sites. We defined compensatory enlargement to be present when the vessel cross-sectional area at the lesion site was larger than that at the proximal reference site, inadequate compensatory enlargement when the vessel cross-sectional area at the lesion site was smaller than that at the distal reference site and intermediate remodeling when the vessel cross-sectional area at the lesion site was intermediate between the two reference sites. RESULTS: Compensatory enlargement was observed in 19 (54%) of 35 lesions, inadequate compensatory enlargement in 9 (26%) of 35 and intermediate remodeling in 7 (20%) of 35. In the inadequate compensatory enlargement group, reduction of the vessel cross-sectional area contributed to 39% of lumen reduction. CONCLUSIONS: Compensatory enlargement commonly (54%) occurs at stenotic coronary lesions. However inadequate compensatory enlargement results in a substantial amount (39%) of the lumen area reduction in 26% of primary coronary artery lesions.