Effect of Simvastatin on Coronary Lesion Site Remodeling: A Serial Intravascular Ultrasound Study

Effects of statins on progression of coronary artery disease as measured by intravascular ultrasound

Intravascular ultrasound (IVUS) is a novel technique that provides an accurate and reproducible method to measure atheroma burden. Statin drugs reduce both atherogenic lipoproteins and cardiovascular morbidity and mortality. Studies assessing the effect of statin treatment on atheroma burden have shown conflicting results. Hence, this meta-analysis was conducted to evaluate the impact of statin therapy on coronary atherosclerosis progression. A systematic search using PubMed, EMBASE, and Cochrane Library databases was performed. Heterogeneity of the studies was analyzed by Cochran's Q statistics. The significance of common treatment effect was assessed by computing common mean difference between the control and treatment groups. A two-sided α error of <0.05 was considered statistically significant (P<.05). Eight trials composed of 919 patients including a placebo group with 458 patients and a treatment group with 461 patients were used. Characteristics of both groups at baseline were similar without any significant difference between them. In the pooled analysis, the common mean difference of coronary atheroma volume between statin therapy and the placebo arm was -3.573 (confidence interval, -4.46 to -2.68; P<.01). This meta-analysis demonstrates that treatment with statins not only slows atherosclerotic plaque progression but may also lead to plaque regression.

Usual dose of simvastatin does not inhibit plaque progression and lumen loss at the peri-stent reference segments after bare-metal stent implantation: a serial intravascular ultrasound analysis

BACKGROUND/AIMS

The aim of this study was to assess the effects of a usual dose of simvastatin (20 mg/day) on plaque regression and vascular remodeling at the peri-stent reference segments after bare-metal stent implantation.

METHODS

We retrospectively investigated serial intravascular ultrasound (IVUS) findings in 380 peri-stent reference segments (184 proximal and 196 distal to the stent) in 196 patients (simvastatin group, n = 132 vs. non-statin group, n = 64). Quantitative volumetric IVUS analysis was performed in 5-mm vessel segments proximal and distal to the stent.

RESULTS

IVUS follow-up was performed at a mean of 9.4 months after stenting (range, 5 to 19 months). No significant differences were observed in the changes in mean plaque plus media (P&M) area, mean lumen area, and mean external elastic membrane (EEM) area from post-stenting to follow-up at both proximal and distal edges between the simvastatin and non-statin group. Although lumen loss within the first 3 mm from each stent edge was primarily due to an increase in P&M area rather than a change in EEM area, and lumen loss beyond 3 mm from each stent edge was due to a combination of increased P&M area and decreased EEM area, no significant differences in changes were observed in P&M, EEM, and lumen area at every 1-mm subsegment between the simvastatin and non-statin group.

CONCLUSIONS

A usual dose of simvastatin does not inhibit plaque progression and lumen loss and does not affect vascular remodeling in peri-stent reference segments in patients undergoing bare-metal stent implantation.

Vessel shrinkage as a sign of atherosclerosis progression in type 2 diabetes: a serial intravascular ultrasound analysis

OBJECTIVE

The aim of this study was to determine the natural history of vascular remodeling of atherosclerotic plaques in patients with type 2 diabetes and the predictors of vessel shrinkage.

RESEARCH DESIGN AND METHODS

In this serial intracoronary ultrasound (IVUS) study, 237 coronary segments from 45 patients enrolled in the DIABETES I, II, and III trials were included. Quantitative volumetric IVUS analyses (motorized pullbacks at 0.5 mm/s) were performed in the same coronary segment after the index procedure and at the 9-month follow-up. Nontreated mild lesions (angiographic stenosis <25%) with > or =0.5 mm plaque thickening and length of > or =5 mm assessed by IVUS were included. Vessel shrinkage was defined as a Deltaexternal elastic membrane area/Deltaplaque area < 0. Statistical adjustment by multiple segments and multiple lesions per patient was performed.

RESULTS

Vessel shrinkage was identified in 37.1% of segments and was associated with a significant decrease in lumen area at 9 months (vessel shrinkage, 10 +/- 4 mm(2) vs. non-vessel shrinkage, 11 +/- 4 mm(2); P = 0.04). Independent predictors of vessel shrinkage were insulin requirements (odds ratio 4.6 [95% CI 1.40-15.10]; P = 0.01), glycated hemoglobin (1.5 [1.05-2.10]; P = 0.02), apolipoprotein B (0.96 [0.94-0.98]; P < 0.001), hypertension (3.7 [1.40-10.30]; P = 0.009), number of diseased vessels (5.6 [2.50-12.50]; P < 0.001), and prior revascularization (17.5 [6.50-46.90]; P < 0.001).

CONCLUSIONS

This serial IVUS study suggests that progression of coronary artery disease in patients with type 2 diabetes may be mainly attributed to vessel shrinkage. Besides, vessel shrinkage is influenced by insulin requirements and metabolic control and is associated with more advanced coronary atherosclerosis.

Comparison of intravascular ultrasound and angiographic assessment of coronary reference segment size in patients with type 2 diabetes mellitus

During percutaneous coronary intervention, the reference segment is assessed angiographically. This report described the discrepancy between angiographic and intravascular ultrasound (IVUS) assessment of reference segment size in patients with type 2 diabetes mellitus. Preintervention IVUS was used to study 62 de novo lesions in 41 patients with type 2 diabetes mellitus. The lesion site was the image slice with the smallest lumen cross-sectional area (CSA). The proximal and distal reference segments were the most normal-looking segments within 5 mm proximal and distal to the lesion. Plaque burden was measured as plaque CSA/external elastic membrane (EEM) CSA. Using IVUS, the reference lumen diameter was 2.80 +/- 0.42 mm and the reference EEM diameter was 4.17 +/- 0.56 mm. The angiographic reference diameter was 2.63 +/- 0.36 mm. Mean difference between the IVUS EEM diameter and angiographic reference diameter was 1.56 +/- 0.55 mm. The mean difference between the IVUS reference lumen diameter and angiographic reference lumen diameter was 0.18 +/- 0.44 mm. Plaque burden in the reference segment correlated inversely with the difference between IVUS and quantitative coronary angiographic reference lumen diameter (slope = -0.12, 95% confidence interval -0.17 to -0.07, p <0.001), but it was not related to the absolute angiographic reference lumen diameter. Thus, reference segment diameters in type 2 diabetic patients were larger using IVUS than angiography, especially in the setting of larger plaque burden. In conclusion, these findings combined with inadequate remodeling may explain the angiographic appearance of small arteries in diabetic patients.