Atherosclerotic coronary plaque regression and the risk of adverse cardiovascular events: a meta-regression of randomized clinical trials.

INTRODUCTION: Atherosclerotic coronary plaques represent the main substrate for coronary artery disease (CAD), and changes in plaque volume, investigated with intravascular ultrasound (IVUS), have been used as surrogate end-points in several clinical trials. However, no conclusive data are available to support the exploitation of IVUS-based plaque changes as a measure of clinically meaningful treatment's effect.
METHODS: Biomed Central, CENTRAL, and Medline/PubMed were searched for randomized clinical trials investigating IVUS variations of plaque and reporting clinical events. End-points of interest were major adverse cardiovascular events (MACE, a composite of death, myocardial infarction [MI] or revascularization), and the rates of MI or revascularization combined. Meta-regression analysis was performed to appraise the association between plaque changes and clinical events during follow-up.
RESULTS: Eleven studies (2 focusing on patients with ACS) with 7864 patients were included. After a median follow-up of 18 months, percentage of atheroma volume (PAV) was 0.50 (95% confidence interval -0.25; 1.00), with a 15.0% (95% CI 9.6%; 22.5%) rate of MACE and a 14.1% (95% CI 10.2%; 19.5%) rate of MI or revascularization. Rates of plaque volume regression were significantly associated with the incidence of MI or revascularization (Beta = 6.3; p = 0.006) but not with MACE (Beta = 0.42; p = 0.208).
CONCLUSION: Regression of atherosclerotic coronary plaque volume may represent a surrogate for myocardial infarction and repeat revascularization but not for MACE. These results derive largely from stable patients, and should consequently be applied only to this population.