iMap intravascular ultrasound evaluation of culprit and non-culprit lesions in patients with ST-elevation myocardial infarction

Cardio-ankle vascular index is associated with coronary plaque composition assessed with iMAP-intravascular ultrasound in patients with coronary artery disease

BACKGROUND

The cardio-ankle vascular index (CAVI) is an indicator of arterial stiffness and has been reported to be associated with the severity of coronary artery disease and cardiovascular events. However, whether CAVI can predict the composition of coronary plaques remains unclear.

METHODS

We enrolled 208 patients who underwent percutaneous coronary intervention (PCI) for culprit lesions evaluated with iMAP-intravascular ultrasound (IVUS), a radiofrequency imaging system for characterizing tissues. iMAP-IVUS classified the culprit plaque composition as fibrotic, lipidic, necrotic, or calcified, and the respective absolute volumes [fibrotic volume (FV), lipidic volume (LV), necrotic volume NV, and calcified volume] and their ratios (%) within the total plaque volume were calculated. A plaque with a median %NV of ≥ 33.2% was defined as a larger NV (LNV) plaque. We measured CAVI and divided the patients into two groups according to CAVI ≥8 (high CAVI, n = 164) or <8 (low CAVI, n = 44).

RESULTS

Culprit plaques had significantly greater absolute NV (p = 0.016), %NV (p = 0.01), and smaller %FV (p = 0.02) in patients with high CAVI than in those with low CAVI. Patients with high CAVI had a higher prevalence of LNV plaques in culprit lesions than those with low CAVI (54% vs. 34%, p = 0.026). CAVI correlated significantly and positively with absolute NV, LV, and negatively with %FV. In logistic regression analysis after adjustment for the classic coronary risk factors and possible variables associated with vulnerable plaques, high CAVI had an independent and significant association with the presence of LNV plaques (OR, 3.37; 95% CI, 1.45-7.79; p = 0.0032).

CONCLUSIONS

A high CAVI is associated with the composition of coronary culprit plaques, particularly increased amount of necrotic tissue, in patients with coronary artery disease undergoing PCI .

Platelet-Derived Growth Factor Predicts Vulnerable Plaque in Patients with Non-ST Elevation Acute Coronary Syndrome

BACKGROUND

Identifying a novel biomarker may contribute to detection of vulnerable plaque in patients with non-ST-elevation acute coronary syndrome (NSTE-ACS). The aim of this study was to investigate the relationship between serum platelet-derived growth factor (PDGF) and vulnerable plaque in patients with moderate and low risk of NSTE-ACS.

METHODS

A total of 65 moderate- and low-risk NSTE-ACS patients with 50-90% coronary stenosis were divided into a vulnerable plaque group (n=46) and a stable plaque group (n=19) according to intravascular ultrasound (IVUS) examinations. Total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and serum PDGF were measured. Plaque characteristics and components were analyzed using gray-scale and iMap-IVUS. Correlation was performed between plaque characteristics and ACS markers. Logistic regression analysis was applied to determine risk factors. Receiver operating characteristic (ROC) curve was used to evaluate the predictive value.

RESULTS

Patients with vulnerable plaque had visible higher levels of TG, LDL-C and PDGF (P < 0.05). There were significant differences in minimal lumen area (MLA), plaque area, plaque burden, fibrotic (FI), clipidic (LI) and necrotic core (NC) between the two groups (P < 0.05). PDGF was weakly correlated with plaque burden (R = 0.428, P < 0.05), as well as moderately correlated with NC (R = 0.669, P < 0.05). Multivariate analysis showed that serum PDGF (OR 4.751, [95% CI 1.534-9.543], P = 0.05) was an independent risk factor of vulnerable plaque. The area under the curve (AUC) was 0.876 (95% CI 0.804-0.948, P=0.001).

CONCLUSIONS

Serum PDGF could potentially predict vulnerable plaque in moderate and low risk of NSTE-ACS patients.

Characteristics of culprit lesions in young patients with metabolic syndrome and classic cardiovascular risk factors

The association between cardiovascular risk factors (CVRFs) and characteristics of coronary plaque in young patients has remained to be fully elucidated. Therefore, the present study sought to determine the association between CVRFs and phenotypes of culprit coronary plaques revealed by optical coherence tomography (OCT) in young patients with stable coronary heart disease (CHD) and acute coronary syndrome (ACS). OCT imaging pullback was performed at corresponding sites on 123 lesions in 123 young patients (age, 36±7 years), including those with stable CHD and ACS. Patients with analyzable OCT images were classified as having thin-cap fibroatheromas (TCFAs), plaque rupture, macrophage accumulation, calcified nodule, vasa vasorum, cholesterol crystal and erosion. TCFAs were more prevalent in patients with metabolic syndrome (MetS) than in those without MetS (P=0.020). Plaque rupture was more common in smokers than in non-smokers (P=0.002). Multivariate analysis indicated that MetS was independently associated with TCFAs (P=0.041) and smoking was independently associated with plaque rupture (P=0.006). Young patients with MetS were demonstrated to have more extensive TCFAs and young smokers had a higher prevalence of culprit plaque rupture.

Feasibility of diagnosing unstable plaque in patients with acute coronary syndrome using iMap-IVUS

OBJECTIVE

To compare the plaque composition between stable and unstable plaques, characterize unstable plaque by using iMap-intravascular ultrasound (IVUS), and quantify the diagnostic criteria for unstable plaque.

METHODS

Thirty-three acute coronary syndrome (ACS) patients who had undergone coronary angiography and IVUS from February 19, 2014 to December 19, 2014 at Peking University People's Hospital were enrolled in the study. Baseline data were collected. The patients were divided into two groups according to their gray-scale IVUS imaging, stable plaque and unstable plaque. A difference-in-difference evaluation was performed using the baseline data and off-line iMap imaging results between the two groups. A receiver operating characteristic (ROC) curve was constructed to obtain the optimal cut-off value to diagnose unstable plaque.

RESULTS

Percentages of fibrotic and necrotic tissues, absolute values of lipidic, necrotic, and calcified tissues, and plaque burden were independent predictors for unstable plaque. Absolute necrotic area was the best predictor and exhibited the highest diagnostic value for plaque vulnerability (area under the curve (AUC)=0.806, P=0.000, 95% CI (0.718, 0.894)). The cut-off score for predicting unstable plaque was 4.0 mm(2).

CONCLUSIONS

This study attempted to propose a cut-off value based on absolute necrotic area using iMap-IVUS to predict plaque vulnerability in patients with ACS. This score might provide a valuable reference for diagnosing unstable plaque.

In-vivo iMap IVUS comparison of in-stent neointima and native coronary atherosclerosis

PURPOSE

The purpose of this study was to compare plaque characteristics of native coronary atherosclerosis and in-stent neointima ten months after ST elevation myocardial infarction (STEMI) using iMap intravascular ultrasound (IVUS).

METHODS

In 49 patients in-stent neointima and the coronary segment proximal to the stent were analyzed with iMap intravascular ultrasound (IVUS) ten months after primary PCI for STEMI.

RESULTS

A higher percentage of necrotic tissue was observed in the proximal coronary segment compared to the in-stent neointima by iMap IVUS (25.5% ± 12.8% vs 12.3% ± 3.3%, p < 0.0001) ten months after STEMI. The proportion of fibrotic tissue in the proximal segment was lower (63.6% ± 14.8% vs 72.0% ± 5.7%, p = 0.002) and the proportion of the lipidic tissue was higher (8.8% ± 3.0% vs 5.9% ± 2.0%, p < 0.0001) than in-stent neointima.

CONCLUSIONS

In patients ten months after STEMI, in-stent neointima contained a higher proportion of fibrotic tissue and lower proportion of necrotic and lipidic tissue compared the native atherosclerotic lesion.

Intravascular Ultrasound-based Imaging Modalities for Tissue Characterisation

Atherosclerosis is the leading cause of cardiovascular mortality and morbidity in the developed world. Intravascular ultrasound (IVUS) is a widely used imaging modality providing complementary diagnostic information to angiography regarding the vessel wall of the coronary arteries. IVUS has been used for assessment of ambiguous angiographic lesions, evaluation of new interventional devices and in atherosclerosis progression-regression trials. However, the standard gray-scale IVUS has limited value for the accurate identification of specific plaque components. This limitation has been partially over- come by introduction of new IVUS-based imaging methods such as: virtual histology IVUS, iMAP-IVUS and Integrated Backscatter IVUS. These methods utilise the ultrasound backscatter signal to enable a more detailed characterization of plaque morphology or tissue characterization and to provide insight on the features of vulnerable plaque.