Original Research. Transluminal Contrast Attenuation Gradient Is Associated with Coronary Plaque Vulnerability — a Computed Tomography Angiography-based Study

The aim of this study was to demonstrate that the transluminal contrast attenuation gradient (TAG), a new CT imaging-derived marker of functional significance of a coronary stenosis, is directly associated with the vulnerability degree of atheromatous coronary plaques. Material and methods: This is a prospective study on 21 patients with 30 atheromatous plaques in the coronary arteries, who underwent cardiac computed tomography angiography (CCTA) for assessment of coronary plaques. Results: Twelve plaques were classified as vulnerable (40%) and 18 plaques (60%) as non-vulnerable. Plaques associated with a TAG value above 10 HU exhibited in a significantly higher proportion CCTA markers of plaque vulnerability, as compared to plaques in which the attenuation gradient was below 10 HU. TAG values >10 HU were associated with a higher amount of plaque volume (107.4 ± 91.2 mm3 vs. 56.0 ± 37.5 mm3, p = 0.009), necrotic core (32.5 ± 36.9 mm3 vs. 3.1 ± 3.2 mm3, p = 0.0003), and fibro-fatty tissue (17.7 ± 16.3 mm3 vs. 4.0 ± 2.6 mm3, p = 0.0002), as compared to those lesions with TAG values below 10 HU. Linear regression analysis revealed a significant correlation between TAG values and CCTA features of plaque instability: necrotic core (r = −0.73, p <0.0001), fibrofatty tissue (r = −0.63, p = 0.0002), and plaque volume (r = −0.48, p = 0.006). Conclusions: In patients with coronary artery disease, contrast attenuation gradient along the coronary plaques, determined by CCTA, correlates with CT markers of plaque vulnerability. Vulnerable coronary plaques are associated with a higher functional significance than the stable ones with a similar anatomic profile.

A Comparative Preliminary Study on CT Contrast Attenuation Gradient Versus Invasive FFR in Patients with Unstable Angina

The aim of this preliminary study was to assess the effectiveness of transluminal contrast attenuation gradient (TAG) determined by computed tomographic angiography (CTA), for the evaluation of the functional significance of coronary artery stenoses in patients with acute coronary syndromes produced by vulnerable coronary plaques, and to demonstrate the correlation between this new parameter and the vulnerability markers of the culprit lesions.

Material and methods: This is a preliminary pilot study on 10 patients with acute coronary syndromes – unstable angina type, who underwent CTA for the assessment of coronary lesions, followed by invasive angiography and the determination of fractional flow reserve (FFR) prior to a revascularization procedure. Patients were divided into 2 groups, according to their FFR values: Group 1 consisted of 6 patients with an FFR value <0.8 (functionally significant lesion), and Group 2 consisted of 4 patients who presented an FFR value >0.8 (functionally non-significant lesion).

Results: FFR values were 0.64 ± 0.07, 95% CI: 0.5–0.7 in Group 1, and 0.86 ± 0.05, 95% CI: 0.7–0.9 in Group 2. Plaques associated with an FFR<0.8 presented a higher amount of plaque volume (192.7 ± 199.7 mm3 vs. 42.1 ± 27.3 mm3, p = 0.1), necrotic core (66.7 ± 72.9 mm3 vs. 10.0 ± 9.3 mm3, p = 0.1), and fibro-fatty tissue (29.7 ± 37.4 mm3 vs. 6.2 ± 3.8 mm3, p = 0.2). At the same time, TAG significantly correlated with the presence of a functionally significant lesion. Coronary lesions associated with low FFR presented significantly higher values of TAG along the plaque as compared with lesions with FFR values >0.8 (TAG values 22.1 ± 5.8 HU vs. 11.7 ± 2.5 HU, p = 0.01). Linear regression identified a significant correlation between TAG and FFR values as a measure of functional significance of the lesion (r = 0.7, p = 0.01).

Conclusions: Contrast attenuation gradient along the culprit lesion, determined by CTA, correlates with the FFR values and with CT markers of plaque vulnerability, indicating that the presence of vulnerability features inside a coronary plaque could increase the functional significance of a coronary lesion.

Clinical update. Computed Tomography — an Emerging Tool for Triple Rule-Out in the Emergency Department. A Review

New imaging tools have been developed in recent years to rapidly and accurately diagnose life-threatening diseases associated with high mortality rates, such as acute coronary syndromes, acute aortic dissection, or pulmonary embolism. The concept of using computed tomographic (CT) assessment in emergency settings is based on the possibility of excluding multiple acute pathologies within one scan. It can be used for patients complaining of acute chest pain of unclear etiology with the possible association of acute coronary dissection or pulmonary embolism, but only a low to moderate risk of developing an acute coronary syndrome. One of the benefits of this protocol is the possibility of decreasing the number of patients who are hospitalized for further investigations. The technique also allows the rapid triage of patients and the safe discharge of those who show negative results. The aim of this review is to summarize the current medical literature regarding the potential use of CT for the triple rule-out (TRO) of coronary etiologies.

Prognostic Value of Epicardial Fat Thickness as a Biomarker of Increased Inflammatory. Status in Patients with Type 2 Diabetes Mellitus and Acute Myocardial Infarction

Introduction: The prognostic value of epicardial fat thickness (EFT) and inflammatory biomarkers such as hs-CRP have not been fully investigated in patients with acute myocardial infarction (AMI) and type 2 diabetes mellitus (DM). The study aim was to assess the correlation between the EFT, the persistence of elevated circulating levels of hs-CRP at 7 ± 2 days after an AMI and the amplitude of the left ventricular (LV) remodeling, in patients with type 2 DM. Methods: The study included 98 patients (45 with type 2 DM and 43 with no DM): Group 1 included 22 low-to-intermediate risk patients (hsCRP <3 mg/l) and Group 2 had 23 high-risk, (hsCRP >3 mg/l) patients. EFT, LV function and remodeling were assessed at baseline and at six months after AMI in both groups. Results: In the diabetic population, the EFT was significantly higher in patients who developed ventricular remodeling as compared with those who did not (8.02 ± 1.80 mm vs. 6.65 ± 2.17 mm, p = 0.02) and significantly correlated with the circulating levels of hs-CRP (r = 0.6251, p <0.0001). The levels of circulating hs-CRP, at baseline, significantly correlated with the RI at six months (r = 0.39, p <0.001). Also, in the diabetic population, the epicardial fat thickness was significantly higher in patients who developed ventricular remodeling as compared with those who did not (8.02 ± 1.80 mm vs. 6.65 ± 2.17 mm, p = 0.02). The epicardial adipose tissue thickness significantly correlated with the circulating levels of hs-CRP (r = 0.6251, p <0.0001), while in the non-diabetic population, EFT was not significantly higher in patients who developed ventricular remodeling as compared with those who did not (71.38 ± 9.09 vs. 67.4 ± 10.17, p = 0.23). Multivariate analysis identified the hs-CRP values (OR: 4.09, p = 0.03) and the EFT (OR: 6.11, p = 0.01) as significant independent predictors for LV remodeling in diabetic population. Conclusions: A larger EFT is associated with a more severe remodeling and impairment of ventricular function in patients with type 2 DM and AMI.

Correlations Between the Contrast Density Gradient along the Coronary Stents and Functional Significance of In-stent Restenosis

Introduction: Coronary artery disease (CAD) is the leading cause of death worldwide and is associated with a significant socio-economic impact. In many cases, patients are treated with implanted coronary stents that carry a significant risk for reobstruction. The aim of our study was to evaluate the importance of coronary computed tomography angiography (CCTA) in evaluating the significance of in-stent restenosis lesions and for establishing the indication for reintervention in these cases.

Materials and methods: We evaluated 25 patients who underwent CCTA examination. We determined the contrast density, expressed in Hounsfield units at two levels, proximal and distal to the stent.

Results: There were no statistically significant differences between the study groups in terms of gender (41.17% females in Group 1 vs. 37.5% in Group 2, p = 1), presence of hypertension (41.17% in Group 1 vs. 62.5% in Group 2, p = 0.31), smoking status (41.17% in Group 1 vs. 37.5% in Group 2, p = 0.31), incidence of dyslipidemia (47.05% vs. 50%, p = 1) and diabetes mellitus (35.29% vs. 0%, p = 0.31). However, the age of the study population was significantly higher in the groups with significant ISR (58.94 ± 8.35 vs. 47.25 ± 11.2, p = 0.02). Patients who showed significant angiographic in-stent stenosis (more than 70%) were found to have a higher transluminal attenuation gradient, compared with those with less severe lesions (14.5 ± 5.4 vs. 5.14 ± 2.4, p = 0.02).

Conclusions: The transluminal attenuation gradient, assessed by CCTA is a non-invasive-derived parameter that can help the clinician to determine the right time for revascularization in case of in-stent restenosis.