Effect of disease eccentricity on compensatory remodeling of coronary arteries: evidence from intravascular ultrasound before interventions

Abstract

Background: Compensatory remodeling occurs to maintain lumen area in human coronary vessels. However, few data exist regarding the relationship between vessel remodeling and plaque distribution. Therefore, we studied coronary sites with or without remodeling by intravascular ultrasound and correlated with disease distribution. Methods and Results: A total of 90 coronary sites with significant stenosis (>50%) from 80 patients were examined before interventions. For identifying the vessel remodeling, external elastic membrane (EEM) area was measured at the stenotic sites and the adjacent proximal and distal sites. The reference EEM area was calculated by averaging proximal and distal EEM areas, and percent enlargement of the EEM area was calculated by the formula: {(stenosis EEM area−reference EEM area)/reference EEM area}×100. Plaque area was determined by reducing the lumen from EEM areas. The maximal (max) and minimal (min) distances from the center of the lumen to the EEM were also measured, and the disease eccentricity index was calculated by the formula: {(max−min)/max}. The lesion was defined as eccentric if the index was >0.5 and as concentric if ≤0.5. There were 39 eccentric and 51 concentric lesions. The enlargement remodeling was observed at 32 lesions with the enlargement of EEM area of 28.0±16.0% (5.5 to 71.3%). Enlargement was more frequently observed in the eccentric than in concentric lesions ( P<0.05). However, within 32 stenoses, which showed enlargement, there was no difference in enlargement between eccentric ( n=19, 25.6±21.0%) and concentric lesions ( n=13, 21.5±12.0%). Also, there was no statistical correlation between the increase in plaque area and % enlargement of EEM area irrespective of plaque morphology. Conclusions: These data demonstrate that in advanced coronary disease compensatory enlargement occurs more frequently at the eccentric than concentric coronary lesions. However, the EEM area was limited to expand regardless of the disease morphology.