Short-term air pollution exposure and mechanisms of plaque instability in acute coronary syndromes: An optical coherence tomography study

BACKGROUND AND AIMS

Air pollution is emerging as an important risk factor for acute coronary syndrome (ACS). In this study, we investigated the association between short-term air pollution exposure and mechanisms of coronary plaque instability evaluated by optical coherence tomography (OCT) imaging in ACS patients.

METHODS

Patients with ACS undergoing OCT imaging were retrospectively selected. Mechanism of culprit lesion instability was classified as plaque rupture (PR) or intact fibrous cap (IFC) by OCT. Based on each case's home address, the mean daily exposures to several pollutants, including particulate matter 2.5 (PM2.5), on the same day of ACS and in the immediate days (up to 6 days) prior to the index ACS, were collected.

RESULTS

139 ACS patients were included [69 (49.6%) had PR and 70 (50.4%) IFC]. Patients with PR, compared to those with IFC, had higher PM2.5 exposure levels on the same day of ACS, without differences in the immediate 6 days before index ACS. At multivariate analysis, PM2.5 exposure on the same day of ACS was the only independent predictor of PR [OR = 1.912 per SD (8.6 μg/m3), CI95 % (1.087-3.364), p = 0.025]. Patients with PR presented a steady increase in PM2.5 daily exposure levels in the days preceding the occurrence of ACS, with a peak the day of ACS (p for trend = 0.042) CONCLUSIONS: This study demonstrates for the first time that a higher short-term PM2.5 exposure, on the same day of ACS, is associated with an increased risk of PR as a pathobiological mechanism of coronary plaque instability.

Exercise Training: The Holistic Approach in Cardiovascular Prevention

Nowadays, there are robust clinical and pathophysiological evidence supporting the beneficial effects of physical activity on cardiovascular (CV) system. Thus, the physical activity is considered a key strategy for CV prevention. In fact, exercise training exerts favourable effects on all risk factors for CV diseases (i.e. essential hypertension, type 2 diabetes mellitus, hypercholesterolemia, obesity, metabolic syndrome, etc…). In addition, all training modalities such as the aerobic (continuous walking, jogging, cycling, etc.) or resistance exercise (weights), as well as the leisure-time physical activity (recreational walking, gardening, etc) prevent the development of the major CV risk factors, or delay the progression of target organ damage improving cardio-metabolic risk. Exercise training is also the core component of all cardiac rehabilitation programs that have demonstrated to improve the quality of life and to reduce morbidity in patients with CV diseases, mostly in patients with coronary artery diseases. Finally, it is still debated whether or not exercise training can influence the occurrence of atrial and ventricular arrhythmias. In this regard, there is some evidence that exercise training is protective predominantly for atrial arrhythmias, reducing the incidence of atrial fibrillation. In conclusion, the salutary effects evoked by physical acitvity are useful in primary and secondary CV prevention.

[Predictors of Coronary Plaque Vulnerability in Patients with Stable Coronary Artery Disease]

Aim      To identify new predictors for vulnerability of atherosclerotic coronary plaques in patients with stable ischemic heart disease (sIHD).Material and methods  This prospective, single-center study included 58 patients with sIHD. Unstable plaques were detected with virtual histology intravascular ultrasound of proximal and medium segments of a coronary artery without significant lesions according to coronarography data. Indexes of inflammation, dyslipidemia and carbohydrate metabolism were considered as candidate predictors for coronary plaque vulnerability.Results In 56 coronary arteries, 58 plaques were detected, 12 of which (20.7 %) were unstable. Vulnerable plaques differed morphologically from stable ones by a greater size of the necrotic core (35.1±8.5 % vs. 24.0±13.2 %; р=0.008), calcified nodules (2.0 [1.0; 5.0] % vs. 1.0 [0; 2.0] %; р=0.006), and a lower content of fibrous components (54.9±10.2 % vs. 66.4±15.8 %; р=0.02). In addition, vulnerable plaques more frequently narrowed the arterial lumen by >70 % of the lumen area (33.3 % vs. 2.2 %; р=0.0006). Correlation analysis showed a negative correlation between the level of high-density lipoproteins (HDL) and calcium volume (r= -0.4104; р=0.023); a positive correlation between the blood glucose level as determined by the oral glucose tolerance test and the lipid component (r=0.48198; р=0.033); and a negative correlation between the apolipoprotein A level and the calcium volume (r= -0.4297; р=0.008).Conclusion      The study demonstrated a high prevalence of vulnerable plaques in nontarget coronary arteries in patients with sIHD. In this process, dyslipidemia indexes (LDL, apolipoproteins A) correlate with the calcium volume whereas blood glucose, as measured in the oral glucose tolerance test, correlates with the lipid component of coronary plaque.

[Predictors of acute coronary syndrome in patients with ischaemic heart disease]

Acute coronary syndrome has for a long time been giving no way of decreasing mortality related to ischaemic heart disease. The primary cause of acute coronary syndrome in the majority of cases is rupture of an unstable atherosclerotic plaque in the coronary artery followed by thrombosis thereof. The main missions of modern cardiology include: assessment of the risk of acute coronary syndrome, identification of predictors of adverse events, and working-out of measures aimed at prevention and optimal management of patients with ischaemic heart disease. This article deals with clinical and morphological factors associated with destabilization of coronary plaques, their rupture, and the development of an acute coronary event.

Clinical and morphological presentations of acute coronary syndrome without coronary plaque rupture - An intravascular ultrasound study

BACKGROUND

Although acute coronary syndrome (ACS) mainly arises from plaque ruptures (PR), precise mechanisms underlying ACS without PR are unknown. We sought to examine clinical, angiographic and intravascular ultrasound (IVUS) characteristics of ACS without PR.

METHODS AND RESULTS

Culprit lesions of 161 ACS patients were categorized by the presence or absence of PR (PR group: n=57, Non-PR group: n=104). Lower abdominal circumference (86±10cm vs 90±9cm, p=0.02), lower prevalence of myocardial infarction (53% vs 82%, p=0.0002), and higher prevalence of definite vasospasm (15% vs 2%, p=0.006) were found in Non-PR group. Morphologically, Non-PR group was associated with simpler Ambrose classification (36% vs 14%, p=0.004), less hypoechoic plaque (45% vs 65%, p=0.04) and lower incidence of IVUS-detected thrombus (21% vs 54%, p<0.0001), compared with PR group. On quantitative IVUS, although minimum lumen area (MLA) was similar between the groups, vessel (14.2±5.4mm(2) vs 17.5±5.1mm(2), p=0.0002) and plaque (11.6±5.0mm(2) vs 14.9±4.9mm(2), p<0.0001) areas were significantly smaller at MLA site in Non-PR group than in PR group. On multivariate analysis, average plaque area was only an independent IVUS-predictor of non-rupture ACS (odds ratio: 0.85, p=0.01).

CONCLUSION

Compared to ACS with PR, non-rupture ACS arise from more hyperechoic (allegedly "stable") plaque with smaller vessel and plaque area, leading to lower incidence of thrombotic occlusion. Coronary vasospasm might be a possible pathogenic mechanism underlying non-rupture ACS.

Imaging of coronary atherosclerosis in various susceptible groups

Coronary artery disease (CAD) is the leading cause of death and disability worldwide. Atherosclerosis, which is the primary pathophysiologic mechanism for the development of plaque leading to CAD, is a multifactorial process resulting from a complex interplay between genetic susceptibility and various risk factors such as hypertension (HT), dyslipidaemia, diabetes mellitus (DM) and smoking. In addition, influences from other disease states such as chronic kidney disease (CKD), obesity and the metabolic syndrome as well as gender and ethnic diversity also contribute to the disease process. Insights from pathological observations and advances in cellular and molecular biology have helped us understand the process of plaque formation, progression and rupture leading to events. Several intravascular imaging techniques such as intravascular ultrasound (IVUS), Virtual histology IVUS (VH-IVUS) and optical coherence tomography (OCT) allow in vivo assessment of plaque burden, plaque morphology and response to therapy. In addition, non invasive assessment using coronary artery calcium (CAC) score allows risk stratification and plaque burden assessment whilst computed tomography coronary angiography (CTCA) allows evaluation of luminal stenosis, plaque characterisation and quantification. This review aims to summarise the results of invasive and non-invasive imaging studies of coronary atherosclerosis seen in various high-risk populations including DM, metabolic syndrome, obesity, CKD and, gender differences and ethnicity. Understanding the phenotype of plaques in various susceptible groups may allow potential development of personalised therapies.

Study of the features of coronary artery atheromatous plaque using intravascular ultrasound in patients with impaired glucose tolerance

Objective

We used intravascular ultrasound (IVUS) to analyze the features of coronary artery atheromatous plaque in patients with impaired glucose tolerance and mild-to-moderate angiographic coronary stenosis. The aim was to determine the clinical significance of plaque characteristics as well as the relationship between hemoglobin A1c (HbA1c) levels and coronary artery lesions.

Methods

HbA1c levels were evaluated in 85 patients (96 lesions), of whom 46 had impaired glucose tolerance (IGT Group) and 39 had normal blood glucose (NBG Group). IVUS was used to analyze the lesion vessel of both groups qualitatively and quantitatively. The external elastic membrane area (EEMA), minimal lumen area (MLA), plaque area (PA), and plaque burden (PB) were measured for both the target lesion and the reference segments (reference external elastic membrane area (REEMA), reference minimal lumen area (RMLA), reference plaque area (RPA), and reference plaque burden (RPB), respectively).

Results

HbA1c levels were significantly higher in the IGT Group than in the NBG Group (P < 0.05). In the IGT Group there was more soft plaque, eccentric plaque, and positive remodeling, and less calcification, while in the NBG Group there was much harder plaque and calcification, no reconstruction, and negative remodeling (P < 0.05). MLA was smaller in the IGT Group than in the NBG Group, while EEMA, PA, and PB were clearly greater (P < 0.05). In the meantime, RMLA was clearly smaller in the IGT Group than in the NBG Group, while RPA and RPB were greater (P < 0.05). HbA1c levels were positively correlated with PA and PB, and negatively correlated with MLA.

Conclusion

IVUS is very valuable for the evaluation of mild-to-moderate coronary lesions. The coronary artery lesions in patients with IGT are more serious and widespread than those in patients with NBG. HbA1c levels might be of some value in assessing the severity of coronary artery lesions.

Comparison of Resolute zotarolimus-eluting stents versus everolimus-eluting stents in patients with metabolic syndrome and acute myocardial infarction: propensity score-matched analysis

BACKGROUND

Despite common use of second-generation drug-eluting stents in treating patients with coronary artery disease, there is lack of data comparing these stents exclusively in patients with acute myocardial infarction (AMI), especially with metabolic syndrome (MetS), which is highly prevalent in AMI and potential to worsen clinical outcomes. The aim of this study was to compare clinical outcomes of everolimus-eluting stent (EES) and Resolute-zotarolimus-eluting stent (R-ZES) in AMI patients with MetS, in terms of stent-related and patient-related outcomes.

METHODS

A total of 3942 AMI patients in the KAMIR (Korea Acute Myocardial Infarction Registry) were grouped according to the presence of MetS and stent type: EES (N=1582) and R-ZES (N=255) in MetS (1837). Target lesion failure (TLF) and patient-oriented composite events (POCE) at 1 year were evaluated.

RESULTS

In MetS patients, TLF (3.7% vs. 2.7%, p=0.592) and POCE (7.9% vs. 6.7%, p=0.764) were similar between EES and R-ZES. Also in Non-MetS patients, TLF (3.9% vs. 3.1%, p=0.307) and POCE (6.4% vs. 7.3%, p=0.866) were similar between 2 groups. TLF was similar between MetS and Non-MetS patients (3.6% vs. 3.8%), while POCEs (7.7% vs. 6.6%) were higher in MetS. Propensity-score matching analysis showed similar results between stent groups in MetS and Non-MetS. In multivariate analysis, left ventricular ejection fraction and symptom-to-door time were independent predictors of TLF and POCE in MetS patients with AMI.

CONCLUSIONS

In MetS patients with AMI, EES and R-ZES showed excellent performance and safety. However, patient-oriented composite events were relatively high, suggesting more efforts to improve them.

Effect of obesity on coronary atherosclerosis and outcomes of percutaneous coronary intervention: grayscale and virtual histology intravascular ultrasound substudy of assessment of dual antiplatelet therapy with drug-eluting stents

BACKGROUND

Obesity is a cardiovascular risk factor, but the obesity paradox in patients undergoing percutaneous coronary intervention is poorly understood.

METHODS AND RESULTS

Assessment of Dual Antiplatelet Therapy With Drug-Eluting Stents (ADAPT-DES) was a prospective, multicenter study of patients undergoing drug-eluting stent implantation. Overall, 780 patients (916 culprit lesions) were evaluated by grayscale and virtual histology-intravascular ultrasound pre-percutaneous coronary intervention. Poststenting intravascular ultrasound was done in 780 patients (894 treated lesions). Patients were divided into body mass index (BMI) tertiles. The high-BMI group had more diabetes mellitus, hypertension, and hyperlipidemia and more frequent plaque ruptures compared with the low-BMI group. At the minimal lumen area site, the high-BMI group had a larger plaque area (11.7 [11.0-12.4] versus 9.8 [9.3-10.4] mm(2)) and a greater plaque burden (77.3% [76.1%-78.5%] versus 74.4% [73.1%-75.8%]) compared with the low-BMI group; however, a larger external elastic membrane area (14.6 [13.8-15.3] versus 12.7 [12.1-13.3] mm(2)) resulted in a similar minimal lumen area compared with the low-BMI group. Post stenting, the high-BMI group had a significantly larger stent area versus the lower-BMI group. At 1-year follow-up, the high-BMI group was associated with less clinically driven target lesion revascularization compared with the low-BMI group in both the overall and the propensity-matched cohorts.

CONCLUSIONS

A high BMI was associated with a greater plaque burden; however, a larger external elastic membrane preserved lumen dimensions and was associated with a larger stent area during intravascular ultrasound-guided stent implantation. Thus, despite more comorbidities, greater plaque burden, and more plaque rupture, a high BMI was not associated with worse outcomes after drug-eluting stent implantation.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00638794.

Does metabolic syndrome predict significant angiographic coronary artery disease?

INTRODUCTION

Metabolic syndrome (MS) is an independent predictor of acute cardiovascular events. However, few studies have addressed the relationship between MS and stable angiographic coronary artery disease (CAD), which has a different pathophysiological mechanism. We aimed to study the independent predictors for significant CAD, and to analyze the impact of MS (by the AHA/NHLBI definition) on CAD.

METHODS

We prospectively included 300 patients, mean age 64±9 years, 59% male, admitted for elective coronary angiography (suspected ischemic heart disease), excluding patients with known cardiac disease. All patients underwent assessment of demographic, anthropometric, and laboratory data and risk factors, and subsequently underwent coronary angiography.

RESULTS

In the study population, 23.0% were diabetic, 40.5% had MS (and no diabetes) and 36.7% had neither diagnosis. Significant CAD was present in 51.3% of patients. CAD patients were older and more frequently male and diabetic, with increased triglycerides and glucose and lower HDL cholesterol. Abdominal obesity was also less prevalent. MS was not associated with the presence of CAD (OR 0.94, 95% CI 0.59-1.48, p=0.778). Of the MS components, the most important predictors of CAD were increased glucose and triglycerides. Abdominal obesity was associated with a lower risk of CAD. In a multivariate logistic regression model for CAD, independent predictors of CAD were age, male gender, glucose and triglycerides. Body mass index had a protective effect.

CONCLUSIONS

Although MS is associated with cardiovascular events, the same was not found for stable angiographically proven CAD. Age, gender, diabetes and triglycerides are the most influential factors for CAD, with abdominal obesity as a protective factor.

Acute coronary syndrome in patients with diabetes mellitus: perspectives of an interventional cardiologist

Diabetes mellitus (DM) is well known to be a coronary artery disease risk equivalent but the cellular mechanism is not completely understood. Recently, virtual histology intravascular ultrasound has demonstrated that patients with DM tend to have a higher occurrence of vulnerable plaques as compared with patients without DM. Insulin-sensitizing agents, such as metformin, have been shown to have limited cardioprotective effects, whereas thiazolidinediones, such as rosiglitazone, have been reported to have possible deleterious effects on cardiovascular mortality in a meta-analysis; however, limited data exist. In contrast, pioglitazone has been reported to have a significant benefit in patients with type 2 DM with acute coronary syndrome (ACS). Animal and human studies have demonstrated the myocardial protective effects of incretins and hold promise in reducing the incidence of major adverse cardiac events in patients with DM. Moreover, in addition to aspirin, the early use of potent antiplatelet agents, such as prasugrel and intravenous glycoprotein IIb-IIIa inhibitors, in patients with DM presenting with ACS is crucial for reducing cardiovascular events in most patients. Thus, patients with DM deserve special attention in global risk factor reduction and development of newer therapeutic agents to improve glycemic control while minimizing or reducing cardiovascular events. This article focuses on ACS in patients with DM, the pathophysiology of "vulnerable blood" in patients with DM, and newer treatment strategies to improve outcomes in this high-risk patient population.

Semiquantified noncalcified coronary plaque in systemic lupus erythematosus

OBJECTIVE

A major cause of morbidity and mortality in systemic lupus erythematosus (SLE) is accelerated coronary atherosclerosis. New technology (computed tomographic angiography) can measure noncalcified coronary plaque (NCP), which is more prone to rupture. We report on a study of semiquantified NCP in SLE.

METHODS

Patients with SLE (n = 147) with no history of cardiovascular disease underwent 64-slice coronary multidetector computed tomography (MDCT). The MDCT scans were evaluated quantitatively by a radiologist, using dedicated software.

RESULTS

The group of 147 patients with SLE was 86% female, 70% white, 29% African American, and 3% other ethnicity. The mean age was 51 years. In our univariate analysis, the major traditional cardiovascular risk factors associated with noncalcified plaque were age (p = 0.007), obesity (p = 0.03; measured as body mass index), homocysteine (p = 0.05), and hypertension (p = 0.04). Anticardiolipin (p = 0.026; but not lupus anticoagulant) and anti-dsDNA (p = 0.03) were associated with higher noncalcified plaque. Prednisone and hydroxychloroquine therapy had no effect, but methotrexate (MTX) use was associated with higher noncalcified plaque (p = 0.0001). In the best multivariate model, age, current MTX use, and history of anti-dsDNA remained significant.

CONCLUSION

Our results suggest that serologic SLE (anti-dsDNA) and traditional cardiovascular risk factors contribute to semiquantified noncalcified plaque in SLE. The association with MTX is not understood, but should be replicated in larger studies and in multiple centers.

Prevalence, Predictors, and Impact of Low High-Density Lipoprotein Cholesterol on in-Hospital Outcomes Among Acute Coronary Syndrome Patients in the Middle East

OBJECTIVE

To estimate the prevalence, predictors, and impact of low high-density lipoprotein cholesterol (HDL-C) on in-hospital outcomes among acute coronary syndrome (ACS) patients in the Middle East.

METHODS

Data were collected prospectively from 6,266 consecutive patients admitted with a diagnosis of ACS and enrolled in the Gulf Registry of Acute Coronary Events (Gulf RACE). A low HDL-C was defined as a level <40 mg/Dl (1.0 mmol/L) for males and <50 mg/dL (1.3 mmol/L) for females. Analyses were performed using univariate and multivariate statistical techniques.

RESULTS

The overall mean age of the cohort was 56±12 years and majority were males (77%). The overall prevalence of low HDL-C was 62%. During in-hospital stay and at discharge, the majority were on statin therapy (83%) while 10% were on other cholesterol lowering agents. After adjustment of demographic and clinical characteristics, the predictors for low HDL-C were higher body mass index (BMI), prior myocardial infarction (MI), diabetes mellitus, smoking and impaired renal function. Multivariable adjustment revealed that low HDL-C was associated with higher in-hospital mortality (odds ratio (OR), 1.54; 95% CI: 1.06-2.24; p=0.022) and cardiogenic shock (OR, 1.61; 95% CI: 1.20-2.14; p=0.001).

CONCLUSIONS

ACS patients in the Middle East have a high prevalence of low HDL-C. Higher BMI, prior MI, diabetes mellitus, smoking, and impaired renal function were predictors of low HDL-C. Significantly higher in-hospital mortality and cardiogenic shock were associated with low HDL-C in men but not in women.