Virtual histology intravascular ultrasound (VH-IVUS) imaging is an innovative tool for the morphological evaluation of coronary atherosclerosis. Evidence for the effects of statin therapy on VH-IVUS parameters have been inconclusive. Consequently, we performed a systematic review and meta-analysis to investigate the impact of statin therapy on plaque volume and its composition using VH-IVUS. The search included PubMed, Cochrane Library, Scopus and Embase (through 30 November 2014) to identify prospective studies investigating the effects of statin therapy on plaque volume and its composition using VH-IVUS. We identified nine studies with 16 statin treatment arms and 830 participants. There was a significant effect of statin therapy in reducing plaque volume (standardized mean difference (SMD): −0.137, 95 % confidence interval (CI): −0.255, −0.019; P = 0.023), external elastic membrane volume (SMD: −0.097, 95 % CI: −0.183, −0.011; P = 0.027) but not lumen volume (SMD: −0.025, 95 % CI: −0.110, +0.061; P = 0.574). There was a significant reduction in fibrous plaque volume (SMD: −0.129, 95 % CI: −0.255, −0.003; P = 0.045) and an increase of dense calcium volume (SMD: +0.229, 95 % CI: +0.008, +0.450; P = 0.043), while changes in fibro-fatty (SMD: −0.247, 95 % CI: −0.592, +0.098; P = 0.16) and necrotic core (SMD: +0.011, 95 % CI: −0.144, +0.165; P = 0.892) tissue volumes were not statistically significant. This meta-analysis indicates a significant effect of statin therapy on plaque and external elastic membrane volumes and fibrous and dense calcium volumes. There was no effect on lumen volume, fibro-fatty and necrotic tissue volumes.

The effect of statin therapy on plasma adiponectin levels has not been conclusively studied. Therefore, we aimed to evaluate this effect through a systematic review and meta-analysis of available randomized controlled trials (RCTs). Quantitative data synthesis was performed using a random-effects model with weighted mean difference (WMD) and 95% confidence interval (CI) as summary statistics. In 30 studies (43 study arms) with 2953 participants, a significant increase in plasma adiponectin levels was observed after statin therapy (WMD: 0.57 μg/mL, 95% CI: 0.18, 0.95, p = 0.004). In subgroup analysis, atorvastatin, simvastatin, rosuvastatin, pravastatin and pitavastatin were found to change plasma adiponectin concentrations by 0.70 μg/mL (95% CI: -0.26, 1.65), 0.50 μg/mL (95% CI: -0.44, 1.45), -0.70 μg/mL (95% CI: -1.08, -0.33), 0.62 μg/mL (95% CI: -0.12, 1.35), and 0.51 μg/mL (95% CI: 0.30, 0.72), respectively. With respect to duration of treatment, there was a significant increase in the subset of trials lasting ≥12 weeks (WMD: 0.88 μg/mL, 95% CI: 0.19, 1.57, p = 0.012) but not in the subset of <12 weeks of duration (WMD: 0.18 μg/mL, 95% CI: -0.23, 0.58, p = 0.390). Random-effects meta-regression suggested a significant association between statin-induced elevation of plasma adiponectin and changes in plasma low density lipoprotein cholesterol levels (slope: 0.04; 95% CI: 0.01, 0.06; p = 0.002). The meta-analysis showed a significant increase in plasma adiponectin levels following statin therapy. Although statins are known to increase the risk for new onset diabetes mellitus, our data might suggest that the mechanism for this is unlikely to be due to a reduction in adiponectin expression.

Raised plasma endothelin-1 (ET-1) levels may be a risk factor for vascular dysfunction and cardiovascular (CV) disease. This meta-analysis assessed the effect of statins on circulating ET-1 concentrations. The search included PUBMED, Cochrane Library, Web of Science, Scopus, and EMBASE up to September 30, 2014 to identify randomized controlled trials (RCTs) with ET-1 measurement during statin therapy. Quantitative data synthesis was performed using a random-effects model, with weighed mean difference (WMD) and 95% confidence interval (CI) as summary statistics. Data from 15 RCTs showed that statin therapy significantly reduces plasma ET-1 concentrations (WMD: -0.30 pg/mL, 95%CI: -0.47, -0.13; p < 0.01). This effect was robust in sensitivity analysis, and not largely affected by the duration of statin therapy (12 week -WMD: -0.19 pg/mL, 95%CI: -0.36, -0.02; p < 0.05) or by dose of statins (40 mg/day - WMD: -0.38 pg/mL, 95%CI: -0.68, -0.08; p = 0.01). Lipophilic (atorvastatin, simvastatin, fluvastatin, and cerivastatin - WMD: -0.34 pg/mL, 95%CI: -0.55, -0.13; p < 0.01), but not a hydrophilic statin (pravastatin - WMD: -0.18 pg/mL, 95%CI: -0.44 -0.08; p > 0.05) had a significant effect in promoting ET-1 reduction. Statin therapy significantly reduces circulating ET-1 concentrations, regardless of treatment duration or dose of statins. This effect of statins may be influenced by statin lipophilicity. There is a need to establish whether lowering ET-1 levels has a beneficial effect on CV events.