Intravascular ultrasound imaging for assessing regression and progression in coronary artery disease

New imaging techniques have been used as surrogate markers of atherosclerotic burden to determine the effects of pharmacologic intervention. The aim of this study was to better determine potential utility and limitations of intravascular ultrasound (IVUS) imaging for assessing regression and progression in coronary artery disease. Medline was searched for randomized trials using IVUS for assessing regression and progression in coronary artery disease (through September 2009). A comparison of IVUS studies with large trials evaluating the same issue with clinical end points was performed. A total of 26 relevant reports (8,631 patients randomized [median 207.5], 5,794 patients analyzed [median 152], duration 2 weeks to 3.4 years [median 12 months]) were identified. Three frequently used IVUS variables were the focus of the analysis: (1) nominal change in plaque volume, (2) percentage change in plaque volume, and (3) nominal change in percentage plaque volume. These variables were presented in 21, 12, and 11 studies, respectively. The variables were the primary end points in 4, 5, and 4 studies, respectively. Large variance with a relatively small difference was noticed in all 3 variables. Fewer than half of the variables showed statistically significant differences in comparing groups. Comparison of IVUS studies with large trials evaluating the same issue with clinical end points showed consistent and inconsistent results. In conclusion, the current method of calculating plaque volume using IVUS seems logical, and some clinical outcomes trials have yielded some evidence. Future studies are needed to determine which IVUS variable is the best surrogate to determine the effects of pharmacologic intervention in patients with coronary artery disease.