Coronary artery distensibility and compensatory vessel enlargement - a novel parameter influencing vascular remodeling?

Vascular remodeling implies the concept of compensatory vessel enlargement to preserve luminal dimensions during atheromatous plaque development. Howe ver, negative remodeling, i.e. vessel shrinkage in response to plaque accum ulation has also been described. So far, the factors influencing positive o r negative remodeling are uncertain. We hypothesized that vascular distensi bility, a measure of vessel compliance, is related to compensatory enlargem ent. In 58 patients undergoing intravascular ultrasound interrogation of a de no vo lesion prior to coronary intervention, the cross-sectional vessel area ( VA), lumen area (LA) and plaque area (PA = VA minus LA) were measured at en d diastole and end systole at the lesion site and at the proximal and dista l reference segments. Positive remodeling was defined to be present when th e VA at the lesion was > 1.05 times larger than that at the proximal refere nce (group A), negative remodeling when the VA at the lesion was < 0.95 of the reference site (group C) and in-between was considered to be intermedia te (group B). Vessel compliance was measured by calculating vascular disten sibility. Results showed a similar LA at the lesion site in all groups (4.18 +/- 2.18 vs. 4.36 +/- 1.19 vs. 3.74 +/- 1.81 mm(2), NS) while VA and PA were signif icantly larger in group A (17.19 +/- 5.08 vs. 14.22 +/- 3.66 and 12.45 +/- 4.82 mm(2), p = 0.005 and 13 +/- 4.55 vs. 9.95 +/- 3.58 and 8.7 +/- 3.83, p = 0.003, respectively). Vascular distensibility at the proximal reference segment was significantly greater in group A (3.55 +/- 2.67 vs. 1.25 +/- 1. 03 and 0.85 +/- 0.73 mmHg(-1), p < 0.001) with a positive correlation betwe en remodeling and distensibility (R = 0.52, p < 0.001). In a multiple regre ssion model including clinical and lesional factors, distensibility was the only predictor of remodeling. In conclusion, these results suggest that compensatory vessel enlargement o ccurs to a greater degree in patients with increased coronary artery disten sibility, which appears to be a predictor for positive remodeling.