Does spotty calcification attenuate the response of nonculprit plaque to statin therapy?: A serial optical coherence tomography study

A Review Paper on Optical Coherence Tomography Evaluation of Coronary Calcification Pattern: Is It Relevant Today?

The process of coronary calcification represents one of the numerous pathophysiological mechanisms involved in the atherosclerosis continuum. Optical coherence tomography (OCT) represents an ideal imaging modality to assess plaque components, especially calcium. Different calcification patterns have been contemporarily described in both early stages and advanced atherosclerosis. Microcalcifications and spotty calcifications correlate positively with macrophage burden and inflammatory markers and are more frequently found in the superficial layers of ruptured plaques in acute coronary syndrome patients. More compact, extensive calcification may reflect a later stage of the disease and was traditionally associated with plaque stability. Nevertheless, a small number of culprit coronary lesions demonstrates the presence of dense calcified plaques. The purpose of the current paper is to review the most recent OCT data on coronary calcification and the interrelation between calcification pattern and plaque vulnerability. How different calcified plaques influence treatment strategies and associated prognostic implications is of great interest.

Association Between Visit-to-Visit Variability in Low-Density Lipoprotein Cholesterol and Plaque Rupture That Leads to Acute Coronary Syndrome

Background: The effect of intraindividual variability in lipid levels on the onset of acute coronary syndrome (ACS) remains uncertain. We evaluated the relationship between intraindividual variability in lipid levels and culprit lesion morphologies by optical coherence tomography (OCT).

Methods and Results: Seventy-four consecutive patients with ACS whose cholesterol levels were assessed ≥3 times during outpatient visits before the onset of ACS were enrolled in the study; 222 patients without significant stenotic lesions were used as a control group. Based on OCT findings of culprit lesions, ACS patients were categorized into a plaque rupture ACS (PR-ACS) group (n=44) or a non-plaque rupture ACS (NPR-ACS) group (erosion or calcified nodule; n=30). Visit-to-visit variability in lipid levels was evaluated using the corrected variability independent of the mean (cVIM). Patients with ACS had significantly higher low-density lipoprotein cholesterol (LDL-C) levels and cVIM in LDL-C than the control group. The PR-ACS group had significantly higher mean LDL-C levels and greater cVIM in LDL-C than the control group. The PR-ACS group had a significantly higher cVIM than the NPR-ACS group, despite similar mean LDL-C levels. Multivariate analysis revealed that higher cVIM of LDL-C was an independent predictor of PR-ACS (odds ratio 1.06; P=0.018).

Conclusions: In addition to the LDL-C level, greater visit-to-visit variability in LDL-C levels may be associated with the onset of ACS induced by plaque rupture.

Morphological Plaque Characteristics and Clinical Outcomes in Patients With Acute Coronary Syndrome and a Cancer History

Background

Although patients with a cancer history have a 2 to 3 times higher risk for acute coronary syndrome (ACS), the morphological characteristics of ACS culprit plaque in those patients and their relations with clinical outcomes remain unknown.

Methods and Results

This retrospective, multicenter, observational cohort study included consecutive patients with ACS who underwent optical coherence tomography‐guided emergent percutaneous coronary intervention. Patients were categorized into those without a cancer history, those with a cancer history, and those currently receiving cancer treatment. ACS culprit lesions were classified as plaque rupture, plaque erosion, or calcified nodule using optical coherence tomography. Plaque erosion frequency was significantly higher in culprit lesions of patients with current cancer and patients with cancer history than in those of patients without cancer history (56.3% versus 61.7% versus 36.5%). Calcified nodule incidence was significantly higher in patients without cancer history than in patients with current cancer and patients without cancer history (patients with current cancer: 12.4% versus patients without cancer history: 25.5% versus patients without cancer history: 12.6%, P<0.001). Cancer history was independently associated with nonplaque rupture (plaque erosion or calcified nodule) in ACS culprit lesions (odds ratio, 4.00; P<0.001). Cancer history was independently associated with major adverse cardiovascular events (hazard ratio [HR], 1.98; P=0.002). Nonplaque rupture in ACS culprit lesions was independently associated with major adverse cardiovascular events (HR, 1.60; P=0.011).

Conclusions

Patients with a cancer history had significantly worse clinical outcomes after ACS than those without a cancer history. Those with a cancer history had significantly higher plaque erosion and calcified nodule incidences in the ACS culprit lesions, which might partly explain their worse clinical outcomes.

Registration

URL: www.umin.ac.jp/ctr/index.htm. Unique Identifier: UMIN000038442.

Intensive statin versus low-dose statin + ezetimibe treatment for fibrous cap thickness of coronary vulnerable plaques

BACKGROUND

Acute coronary syndromes mainly result from abrupt thrombotic occlusion caused by atherosclerotic vulnerable plaques (VPs) that suddenly rupture or erosion. Fibrous cap thickness (FCT) is a major determinant of the propensity of a VP to rupture and is recognized as a key factor. The intensive use of statins is known to have the ability to increase FCT; however, there is a risk of additional adverse effects. However, lower dose statin with ezetimibe is known to be tolerable by patients. The present study aimed to investigate the effect of intensive statin vs. low-dose stain + ezetimibe therapy on FCT, as evaluated using optical coherence tomography.

METHOD

Patients who had VPs (minimum FCT <65 μm and lipid core >90°) and deferred from intervention in our single center from January 2014 to December 2018 were included in the trial. They were divided into the following two groups: intensive statin group (rosuvastatin 15-20 mg or atorvastatin 30-40 mg) and combination therapy group (rosuvastatin 5-10 mg or atorvastatin 10-20 mg + ezetimibe 10 mg). At the 12-month follow-up, we compared the change in the FCT (ΔFCT%) between the two groups and analyzed the association of ΔFCT% with risk factors. Fisher exact test was used for all categorical variables. Student's t test or Mann-Whitney U-test was used for analyzing the continuous data. The relationship between ΔFCT% and risk factors was analyzed using linear regression analysis.

RESULT

Total 53 patients were finally enrolled, including 26 patients who were in the intensive statin group and 27 who were in the combination therapy group. At the 12-month follow-up, the serum levels of total cholesterol (TC), total triglyceride, low-density lipoprotein (LDL-C), hypersensitive C-reactive protein (hs-CRP), and lipoprotein-associated phospholipase A2 (Lp-PLA2) levels were reduced in both the groups. The ΔTC%, ΔLDL-C%, and ΔLp-PLA2% were decreased further in the combination therapy group. FCT was increased in both the groups (combination treatment group vs. intensive statin group: 128.89 ± 7.64 vs. 110.19 ± 7.00 μm, t = -9.282, P < 0.001) at the 12-month follow-up. The increase in ΔFCT% was more in the combination therapy group (123.46% ± 14.05% vs. 91.14% ± 11.68%, t = -9.085, P < 0.001). Based on the multivariate linear regression analysis, only the serum Lp-PLA2 at the 12-month follow-up (B = -0.203, t = -2.701, P = 0.010), ΔTC% (B = -0.573, t = -2.048, P = 0.046), and Δhs-CRP% (B = -0.302, t = -2.963, P = 0.005) showed an independent association with ΔFCT%.

CONCLUSIONS

Low-dose statin combined with ezetimibe therapy maybe provide a profound and significant increase in FCT as compared to intensive statin monotherapy. The reductions in Lp-PLA2, ΔTC%, and Δhs-CRP% are independently associated with an increase in FCT.

Optical Coherence Tomography Predictors for a Favorable Vascular Response to Statin Therapy

Background

Specific plaque phenotypes that predict a favorable response to statin therapy have not been systematically studied. This study aimed to identify optical coherence tomography predictors for a favorable vascular response to statin therapy.

Methods and Results

Patients who had serial optical coherence tomography imaging at baseline and at 6 months were included. Thin‐cap area (defined as an area with fibrous cap thickness <200 μm) was measured using a 3‐dimensional computer‐aided algorithm, and changes in the thin‐cap area at 6 months were calculated. A favorable vascular response was defined as the highest tertile in the degree of reduction of the thin‐cap area. Macrophage index was defined as the product of the average macrophage arc and length of the lesion with macrophage infiltration. Layered plaque was defined as a plaque with 1 or more layers of different optical density. In 84 patients, 140 nonculprit lipid plaques were identified. In multivariable analysis, baseline thin‐cap area (odds ratio [OR] 1.442; 95% CI, 1.024–2.031, P=0.036), macrophage index (OR, 1.031; 95% CI, 1.002–1.061, P=0.036), and layered plaque (OR, 2.767; 95% CI, 1.024–7.479, P=0.045) were identified as the significant predictors for a favorable vascular response. Favorable vascular response was associated with a decrease in the macrophage index.

Conclusions

Three optical coherence tomography predictors for a favorable vascular response to statin therapy have been identified: large thin‐cap area, high macrophage index, and layered plaque. Favorable vascular response to statin was correlated with signs of decreased inflammation.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT01110538.

Insulin-like growth factor-1 levels predict myocardial injury and infarction after elective percutaneous coronary intervention: an optical coherence tomography study

INTRODUCTION

Periprocedural myocardial necrosis, which can range from a low level elevation of cardiac biomarkers to a large myocardial infarction (MI), is a common complication after percutaneous coronary intervention (PCI).

AIM

We hypothesized that insulin-like growth factor-1 (IGF-1) levels may play a protective role in myocardial injury after coronary stent placement and aimed to investigate the relationship between IGF-1 levels and plaque characteristics assessed by optical coherence tomography (OCT).

MATERIAL AND METHODS

Between May 2015 and December 2015 we prospectively enrolled 74 patients with stable angina pectoris in whom single de novo coronary artery stenosis was present. PCI was performed according to standard methods. OCT was applied to all patients. TnT was analyzed at admission, before PCI and at 6, 12, 24 and 48 h after PCI. Serum IGF-1 was measured prior to PCI.

RESULTS

A total of 25 (33.7%) patients had periprocedural myocardial injury or type 4a myocardial infarction, and 49 (66.2%) patients had no events. IGF-1 level and reference intimal thickness, medial thickness, and plaque fibrous cap thickness in OCT had strong correlations (r = 0.88, 0.80 and 0.88 respectively, p < 0.001). IGF-1 was an independent predictor of periprocedural myocardial injury or type 4a MI in univariate (OR = 0.929, 95% CI: 0.895-0.964, p < 0.001) and multivariate regression analysis (OR = 0.757, 95% CI: 0.575-0.998, p = 0.04). Based on ROC analysis, the best cut-off value of IGF-1 for predicting periprocedural myocardial injury or type 4a myocardial infarction was 144.5 ng/ml, with a maximum sensitivity of 88% and specificity of 77.6% (AUC = 0.80, 95% CI: 0.69-0.88, p < 0.0001).

CONCLUSIONS

The results from this study indicate that low IGF-1 levels are associated with plaque instability assessed by OCT. Low IGF-1 levels may identify patients who are at increased risk for periprocedural myocardial injury/infarction.

Calcification in Atherosclerotic Plaque Vulnerability: Friend or Foe?

Calcification is a clinical marker of atherosclerosis. This review focuses on recent findings on the association between calcification and plaque vulnerability. Calcified plaques have traditionally been regarded as stable atheromas, those causing stenosis may be more stable than non-calcified plaques. With the advances in intravascular imaging technology, the detection of the calcification and its surrounding plaque components have evolved. Microcalcifications and spotty calcifications represent an active stage of vascular calcification correlated with inflammation, whereas the degree of plaque calcification is strongly inversely related to macrophage infiltration. Asymptomatic patients have a higher content of plaque calcification than that in symptomatic patients. The effect of calcification might be biphasic. Plaque rupture has been shown to correlate positively with the number of spotty calcifications, and inversely with the number of large calcifications. There may be certain stages of calcium deposition that may be more atherogenic. Moreover, superficial calcifications are independently associated with plaque rupture and intraplaque hemorrhage, which may be due to the concentrated and asymmetrical distribution of biological stress in plaques. Conclusively, calcification of differential amounts, sizes, shapes, and positions may play differential roles in plaque homeostasis. The surrounding environments around the calcification within plaques also have impacts on plaque homeostasis. The interactive effects of these important factors of calcifications and plaques still await further study.