Angiographic assessment of the culprit coronary artery lesion before acute myocardial infarction

Stable Coronary Artery Disease: Who Finally Benefits from Coronary Revascularization in the Modern Era? The ISCHEMIA and Interim ISCHEMIA-EXTEND Analysis

Coronary revascularization is one of the most studied treatment modalities in cardiology; however, there is no consensus among experts about its indications in patients with stable coronary artery disease (SCAD). Contemporary data regarding the role of revascularization in SCAD are in clear conflict with the current European guidelines. This article discusses the main statements of the most significant American and European Guidelines on myocardial revascularization of the last decade and also analyzes the appropriateness of revascularization to improve the prognosis and symptoms in SCAD in the light of new research data, primarily the ISCHEMIA study (NCT01471522) and the ACC/AHA 2021 Revascularization Guidelines based on them. Data on the revascularization in SCAD obtained after the completion of ISCHEMIA (including the interim analysis of ISCHEMIA-EXTEND) and their potential significance are discussed. The results of ISCHEMIA sub-analyses in the most important "controversial" subgroups (3-vessel disease, proximal left anterior descending artery disease, strongly positive stress test, etc.) are reviewed, as are the results of the ISCHEMIA-CKD substudy in patients with severe chronic kidney disease (CKD).

Optimum Treatment Strategy in Chronic Coronary Syndromes: the New Trials vs the Current Guidelines

Coronary revascularization is one of the most studied types of interventions in cardiology, but there is no consensus among specialists about the indications for its implementation in patients with chronic coronary syndromes (CCS). The data of recently completed clinical trials on the role of revascularization in CCS clearly contradict the current Guidelines, emphasizing the high effectiveness of modern conservative therapy. This paper discusses the main recommendations of the most significant American and European Guidelines on myocardial revascularization, and also analyzes the appropriateness of revascularization to improve the prognosis and symptoms in chronic coronary syndromes in view of the new research data, primarily the ISCHEMIA study (NCT01471522). Its strengths and limitations are discussed in detail. The data on the expediency of revacularization in CCS, obtained after the completion of ISCHEMIA and its potential significance, as well as subgroup analyses of ISCHEMIA, including in the most important ‘problem’ subgroups (3-vessel disease, proximal LAD disease, severe ischemia on stress test, etc.) are discussed. The paper also discusses the important achievements in modern drug therapy of chronic coronary syndromes, primarily antithrombotic therapy. The data of the COMPASS study (NCT01776424) are discussed, based on which the addition of a second antithrombotic drug – rivaroxaban in a small dose (2.5 mg BID) – is recommended for patients with CCS without atrial fibrillation who have high-risk characteristics. Indications the administration of dual antithrombotic therapy to patients with CCS, comparative results of its various regimens in relation to the prevention of cardiovascular complications, the risk of bleeding and the net clinical effect are given.

Vessel membrane segmentation and calcification location in intravascular ultrasound images using a region detector and an effective selection strategy

BACKGROUND AND OBJECTIVE

Segmenting vessel membranes and locating the calcific region in intravascular ultrasound (IVUS) images aid physicians in the diagnosis of atherosclerosis. However, the manual extraction of the media adventitia (MA)/lumen border and calcification location are cumbersome due to the excessive number of IVUS frames. Moreover, most existing (semi-)automatic detection methods cannot achieve both vessel membrane extraction and calcification location simultaneously, and they are unable to detect vessel membranes in IVUS frames from different acquisition systems.

METHOD

A fully automatic approach is proposed based on extremal regions and a flexible selection strategy to extract vessel membranes in different IVUS frames and locate the calcific region in high-frequency ones. Three main steps are included in the algorithm. First, a region detector is employed to extract extremal regions from an IVUS image. Then, according to the selection strategy, a part of the extracted regions is selected. At the same time, the calcification is located according to its special acoustic properties. Next, approximate MA and lumen border segmentation is achieved based on the selected extremal regions and the located calcification in polar coordinates. Finally, the final segmentation results are obtained by smoothing the approximate values.

RESULT

To demonstrate the feasibility of the method, it was evaluated based on a standard public dataset. Furthermore, to quantitatively evaluate the segmentation performance, the Hausdorff distance (HD), Jaccard measure (JM) and percentage of area difference (PAD) were used. The results show that a mean HD of 1.13/1.21 mm, a mean JM of 0.83/0.77 and a mean PAD of 0.11/0.23 are achieved for MA/lumen border detection in 77 40-MHz IVUS images. For MA/lumen border extraction in 435 20-MHz IVUS frames, the average HD, JM and PAD values are 0.47/0.28 mm, 0.84/0.89 and 0.13/0.10, respectively. In addition, the approach successfully achieves calcification location in 40-MHz IVUS frames. In comparison with other published methods, the method proposed in this study is competitive.

CONCLUSION

According to these results, our strategy can extract MA/lumen borders in different IVUS frames and effectively locate calcification in high-frequency IVUS frames.

Appropriateness of diagnostic coronary angiography as a measure of cardiac ischemia testing in non-emergency patients - a retrospective cross-sectional analysis

Background

Adequate application of guidelines concerning non-invasive ischemia testing (NIIT) could avoid inappropriate invasive testing in non-emergency situations. Hardly any data exists regarding frequency and appropriateness of diagnostic coronary angiography (CA). The aim of this study was to evaluate the proportion and predictors of patients without NIIT prior to elective purely diagnostic CA without therapeutic intervention.

Methods

Retrospective cross-sectional analysis of insurance claims data from 2012 and 2013. Patients <18 years, acute cardiac ischemia and emergency procedures and patients insured in a managed care model were excluded from analysis. The proportion of patients with NIIT procedures (stress-ECG, transthoracic echocardiography, stress echocardiography, scintigraphy, computer tomography, heart MRI) undertaken within two months before diagnostic CA was assessed. Multiple logistic regression analysis was applied to investigate independent determinants for receiving NIIT.

Findings

2714 patients were included for analysis. 37.5% (1018) did not receive any NIIT before CA. When high risk patients (patients having received therapeutic cardiac intervention within one month after or 18 months prior to diagnostic CA, n = 766) were excluded 34.3% (669) did not receive NIIT before CA. High risk status as well as >6 chronic comorbidities were independently associated with a lower proportion of NIIT (p<0.0001, OR 0.607 and p = 0.0041, OR 0.648), when additionally controlled for age, sex, language area, insurance coverage, inpatient treatment, cardiovascular medication and lower number of chronic comorbidities. Age (p<0.05, OR 1.009) and intake of oral antiplatelet therapy (p<0.0001, OR 1.914) were independently associated with a higher proportion of NIIT when controlled for the mentioned cofactors.

Conclusions

Our data show that despite the existence of guidelines a substantial overuse of a potentially harmful and inappropriate diagnostic intervention is performed suggesting the need for improvement of diagnostic pathways prior to invasive testing.

Evaluation of solid organ transplant candidates for coronary artery disease

Solid organ transplantation has increased in frequency in the United States, having evolved from an area of experimentation into accepted therapy for end-organ failure. As organ transplantation has become more common, the average age of transplant recipients has increased, thus increasing the potential for multiple comorbidities including coronary artery disease (CAD). CAD has been shown to be a major cause of morbidity and mortality in kidney, lung and liver transplant recipients. Identification of CAD in solid organ transplant candidates allows for stratification of short- and long-term risk, ensuring proper use of valuable allograft resources while guiding further patient management. Assessment of asymptomatic transplant candidates for CAD is difficult. Many patients undergo stress echocardiography or nuclear imaging, which have demonstrated inconsistent rates of sensitivity and specificity for the detection of CAD in these patient populations. Cardiac computed tomography is a potential tool for detecting CAD in these populations, but has questionable utility at this time. Coronary angiography has an important role in detecting CAD in high-risk transplant candidates, affecting their long-term management and risk.

A state-of-the-art review on segmentation algorithms in intravascular ultrasound (IVUS) images

Over the past two decades, intravascular ultrasound (IVUS) image segmentation has remained a challenge for researchers while the use of this imaging modality is rapidly growing in catheterization procedures and in research studies. IVUS provides cross-sectional grayscale images of the arterial wall and the extent of atherosclerotic plaques with high spatial resolution in real time. In this paper, we review recently developed image processing methods for the detection of media-adventitia and luminal borders in IVUS images acquired with different transducers operating at frequencies ranging from 20 to 45 MHz. We discuss methodological challenges, lack of diversity in reported datasets, and weaknesses of quantification metrics that make IVUS segmentation still an open problem despite all efforts. In conclusion, we call for a common reference database, validation metrics, and ground-truth definition with which new and existing algorithms could be benchmarked.

Risk stratification of patients suspected of coronary artery disease: comparison of five different models

OBJECTIVE

To compare the performance of five risk models (Diamond-Forrester, the updated Diamond-Forrester, Morise, Duke, and a new model designated COronary Risk SCORE (CORSCORE) in predicting significant coronary artery disease (CAD) in patients with chest pain suggestive of stable angina pectoris.

METHODS

Retrospective cohort for creation of CORSCORE by means of logistic regression analysis. Prospective cohort for validation of the five risk models using receiver operating characteristics (ROC) curve analysis, net reclassification improvement (NRI), and integrated discrimination improvement (IDI). Significant CAD was defined as lumen area diameter reduction ≥50% at coronary angiography. All risk models include information on age, sex, and symptoms. In addition the Duke, Morise, and CORSCORE models include information on tobacco use and hypercholesterolemia. Duke and Morise also include information on diabetes. History of myocardial infarction is used by the Duke and CORSCORE models whereas hypertension is included in the Morise and CORSCORE models. The Duke model includes information on electrocardiogram (ECG) changes and the Morise model includes information on family history, body mass index, obesity, and oestrogen status.

RESULTS

4781 retrospective and 633 prospective consecutive patients referred for coronary angiography were included. The area under the ROC for the updated Diamond-Forrester, Duke, and CORSCORE was significantly larger than for the Diamond-Forrester (p≤0.001). The IDI was significantly higher for the Duke as compared to all other models (p≤0.006).

CONCLUSION

The Duke, updated Diamond-Forrester, and CORSCORE risk models are most efficient in predicting CAD in a contemporary cohort of patients with symptoms suggestive of angina. The updated Diamond-Forrester may most operational in daily clinical practice since it is calculated from the lowest number of clinical variables.

Pitavastatin: finding its place in therapy

Dyslipidaemia is a major risk factor for cardiovascular (CV) disease. Despite the widespread availability of effective lipid-lowering agents, an unacceptably large proportion of patients fail to attain their target low-density lipoprotein cholesterol (LDL-C) level in clinical practice. Reasons for this include undertreatment, poor adherence/persistence with therapy and failure to address non-LDL-C residual risk factors such as high levels of triglycerides, low high-density lipoprotein cholesterol (HDL-C) concentrations and raised apolipoprotein B: apolipoprotein A1 ratios. Pitavastatin is a novel, well-tolerated statin with a noninferior or superior lipid-lowering efficacy to comparable doses of atorvastatin, simvastatin, and prava-statin in a wide range of patients with hypercholesterolemia or combined dyslipidaemia. Compared with other statins, pitavastatin produces consistently greater increases in HDL-C levels that are sustained over the long term. In addition to pravastatin's potent effects on lipid profiles, a number of pleiotropic benefits have been identified that may contribute to a reduction in residual cardiovascular risk in people with dyslipidaemia and could partly account for pitavastatin's ability to regress coronary plaques in patients with acute coronary syndrome. Pitavastatin's unique metabolic profile results in a high efficacy at low (1-4 mg) doses and minimal drug interactions with cytochrome CYP3A4 substrates, making it an excellent choice for people requiring multiple medications. Although future trials are required to assess the impact of pitavastatin treatment on CV morbidity and mortality, studies to date suggest that pitavastatin will play an important role in the future management of dyslipidaemia and in the overall reduction of CV risk.

Predictors of cardiovascular events after liver transplantation: a role for pretransplant serum troponin levels

Cardiovascular complications are major causes of morbidity and mortality after liver transplantation. Identifying candidates at highest risk of postoperative complications is a cornerstone of optimizing outcomes and utility. Using traditional cardiac risk factors in addition to C-reactive protein (CRP) levels, troponin levels, and echocardiographic parameters before transplantation, we sought to define cardiac risk so that we could predict cardiovascular events after transplantation. From December 1998 to December 2001, 230 adult patients who underwent liver transplantation with a median follow-up of 8.2 years were studied. The risk factors for cardiac disease were as follows: male gender with a mean age of approximately 50 years (57%), smoking history (60%), diabetes (23%), hypertension (19%), elevated troponin (25%), elevated CRP (25%), and preexisting cardiac disease (16%). Fifty-nine cardiac events occurred over 8.2 years. Risk factors (univariate analysis) for first cardiac events included age in decades [hazard ratio (HR) = 1.31, P = 0.047], diabetes (HR = 2.20, P = 0.004), prior cardiovascular disease (HR = 4.77, P < 0.0001), a troponin I level > 0.07 ng/mL (HR = 2.00, P = 0.023), left ventricular hypertrophy (HR = 2.06, P = 0.047), stress wall abnormalities (HR = 2.25, P = 0.018), and ischemia on stress imaging (HR = 2.89, P = 0.015). Multivariate analysis confirmed age, diabetes, a troponin I level > 0.07, and prior cardiac disease as independent risk factors for posttransplant cardiac events. In conclusion, pretransplant elevated troponin levels, diabetes, and a history of cardiovascular disease, alone or in combination, are strongly associated with the occurrence of posttransplant cardiovascular events.

Magnetic resonance imaging of carotid atherosclerotic plaque in clinically suspected acute transient ischemic attack and acute ischemic stroke

BACKGROUND

Carotid atherosclerotic plaque rupture is thought to cause transient ischemic attack (TIA) and ischemic stroke (IS). Pathological hallmarks of these plaques have been identified through observational studies. Although generally accepted, the relationship between cerebral thromboembolism and in situ atherosclerotic plaque morphology has never been directly observed noninvasively in the acute setting.

METHODS AND RESULTS

Consecutive acutely symptomatic patients referred for stroke protocol magnetic resonance imaging/angiography underwent additional T1- and T2-weighted carotid bifurcation imaging with the use of a 3-dimensional technique with blood signal suppression. Two blinded reviewers performed plaque gradings according to the American Heart Association classification system. Discharge outcomes and brain magnetic resonance imaging results were obtained. Image quality for plaque characterization was adequate in 86 of 106 patients (81%). Eight TIA/IS patients with noncarotid pathogenesis were excluded, yielding 78 study patients (38 men and 40 women with a mean age of 64.3 years, SD 14.7) with 156 paired watershed vessel/cerebral hemisphere observations. Thirty-seven patients had 40 TIA/IS events. There was a significant association between type VI plaque (demonstrating cap rupture, hemorrhage, and/or thrombosis) and ipsilateral TIA/IS (P<0.001). A multiple logistic regression model including standard Framingham risk factors and type VI plaque was constructed. Type VI plaque was the dominant outcome-associated observation achieving significance (P<0.0001; odds ratio, 11.66; 95% confidence interval, 5.31 to 25.60).

CONCLUSIONS

In situ type VI carotid bifurcation region plaque identified by magnetic resonance imaging is associated with ipsilateral acute TIA/IS as an independent identifier of events, thereby supporting the dominant disease pathophysiology.

Cardiovascular molecular imaging of apoptosis

Introduction

Molecular imaging strives to visualise processes at the molecular and cellular level in vivo. Understanding these processes supports diagnosis and evaluation of therapeutic efficacy on an individual basis and thereby makes personalised medicine possible.

Apoptosis and molecular imaging

Apoptosis is a well-organised mode of cell suicide that plays a role in cardiovascular diseases (CVD). Apoptosis is associated with loss of cardiomyocytes following myocardial infarction, atherosclerotic plaque instability, congestive heart failure and allograft rejection of the transplanted heart. Thus, apoptosis constitutes an attractive target for molecular imaging of CVD. Our current knowledge about the molecular players and mechanisms underlying apoptosis offers a rich palette of potential molecular targets for molecular imaging. However, only a few have been successfully developed so far.

Aims

This review highlights aspects of the molecular machinery and biochemistry of apoptosis relevant to the development of molecular imaging probes. It surveys the role of apoptosis in four major areas of CVD and portrays the importance and future perspectives of apoptosis imaging. The annexin A5 imaging protocol is emphasised since it is the most advanced protocol to measure apoptosis in both preclinical and clinical studies.

Imaging techniques for the vulnerable coronary plaque

The goal of this article is to illustrate the main invasive and noninvasive diagnostic modalities to image the vulnerable coronary plaque, which is responsible for acute coronary syndrome. The main epidemiologic and histological issues are briefly discussed in order to provide an adequate background. Comprehensive coronary atherosclerosis imaging should involve visualization of the entire coronary artery tree and plaque characterization, including three-dimensional morphology, relationship with the lumen, composition, vascular remodelling and presence of inflammation. No single technique provides such a comprehensive description, and no available modality extensively identifies the vulnerable plaque. In particular, we describe multislice computed tomography, which at present seems to be the most promising noninvasive tool for an exhaustive image-based quantification of coronary atherosclerosis.

Comparison of intensive and low-dose atorvastatin therapy in the reduction of carotid intimal-medial thickness in patients with coronary heart disease

BACKGROUND

Intensive statin therapy has been shown to improve prognosis in patients with coronary heart disease (CHD). It is unknown whether such benefit is mediated through the reduction of atherosclerotic plaque burden.

AIM

To examine the efficacy of high-dose atorvastatin in the reduction of carotid intimal-medial thickness (IMT) and inflammatory markers in patients with CHD.

DESIGN

Randomised trial.

SETTING

Single centre.

PATIENTS

112 patients with angiographic evidence of CHD.

INTERVENTIONS

A high dose (80 mg daily) or low dose (10 mg daily) of atorvastatin was given for 26 weeks.

MAIN OUTCOME MEASURES

Carotid IMT, C-reactive protein (CRP) and proinflammatory cytokine levels were assessed before and after therapy.

RESULTS

The carotid IMT was reduced significantly in the high-dose group (left: mean (SD), 1.24 (0.48) vs 1.15 (0.35) mm, p = 0.02; right: 1.12 (0.41) vs 1.01 (0.26) mm, p = 0.01), but was unchanged in the low-dose group (left: 1.25 (0.55) vs 1.20 (0.51) mm, p = NS; right: 1.18 (0.54) vs 1.15 (0.41) mm, p = NS). The CRP levels were reduced only in the high-dose group (from 3.92 (6.59) to 1.35 (1.83) mg/l, p = 0.01), but not in the low-dose group (from 2.25 (1.84) to 3.36 (6.15) mg/l, p = NS). A modest correlation was observed between the changes in carotid IMT and CRP (r = 0.21, p = 0.03).

CONCLUSIONS

In patients with CHD, intensive atorvastatin therapy results in regression of carotid atherosclerotic disease, which is associated with reduction in CRP levels. On the other hand, a low-dose regimen only prevents progression of the disease.

Imaging apoptosis for detecting plaque instability: rendering death a brighter facade

The relatively poor correlation between the risk of atherosclerotic plaque rupture and the degree of luminal obstruction before this event implies a strong imperative for in vivo detection of the processes underlying progressive plaque destabilization. In addition to the morphologic characteristics, apoptosis and inflammation comprise two important indicators of plaque instability. Apoptotic macrophage death results in enlargement of the plaque necrotic core and positive vascular remodelling, whereas apoptosis of the smooth muscle cells leads to attenuation of the fibrous cap. Imaging of apoptotic cells with annexin A5 provides an opportunity for the non-invasive assessment of cell death, and hence plaque vulnerability. The clinical detection of apoptosis could therefore promote the development of novel intervention strategies.

Angiographic coronary artery disease is associated with progressively higher levels of fasting plasma glucose

This study evaluated the association between progressively higher levels of fasting glycemia (G) and insulin resistance parameters with coronary artery disease (CAD) in patients referred for coronary angiography. All 145 patients (age 58.4+/-0.9 years, 51.7% men) underwent clinical and laboratory evaluation before coronary angiography and subjects were divided into four groups: normal (N, <88 mg/dl), high-normal (H-N, 89-99 mg/dl), impaired fasting glucose (IFG, 100-125 mg/dl) and diabetes (DM, >126 mg/dl or known diabetics). Arteriographic evidence of CAD was determined by two criteria: (1) a 30% or greater diameter stenosis in at least one major coronary artery; (2) a 70% or greater diameter stenosis in at least one major coronary artery. HOMA-IR increased progressively according to each group: N=1.74+/-0.2, H-N=3.14+/-0.3, IFG=4.67+/-0.6 and DM=8.00+/-2.9; p=0.001. The proportion of patients with CAD according to both criteria increased with each G level: CAD criteria 1: N=39.4%, H-N=50%, IFG=60% and DM=69.6%, p=0.006; CAD criteria 2: N=27.3%, H-N=30%, IFG=36% and DM=50%, p=0.03. We demonstrated a significant association between subtle disturbances of the glucose metabolism, assessed by subnormal levels of fasting glucose and insulin resistance parameters, and angiographically documented coronary artery disease.

A hypothesis for vulnerable plaque rupture due to stress-induced debonding around cellular microcalcifications in thin fibrous caps

In this article, we advance a hypothesis for the rupture of thin fibrous cap atheroma, namely that minute (10-mum-diameter) cellular-level microcalcifications in the cap, which heretofore have gone undetected because they lie below the visibility of current in vivo imaging techniques, cause local stress concentrations that lead to interfacial debonding. New theoretical solutions are presented for the local stress concentration around these minute spherical inclusions that predict a nearly 2-fold increase in interfacial stress that is relatively insensitive to the location of the hypothesized microinclusions in the cap. To experimentally confirm the existence of the hypothesized cellular-level microcalcifications, we examined autopsy specimens of coronary atheromatous lesions using in vitro imaging techniques whose resolution far exceeds conventional magnetic resonance imaging, intravascular ultrasound, and optical coherence tomography approaches. These high-resolution imaging modalities, which include confocal microscopy with calcium-specific staining and micro-computed tomography imaging, provide images of cellular-level calcifications within the cap proper. As anticipated, the minute inclusions in the cap are very rare compared with the numerous calcified macrophages observed in the necrotic core. Our mathematical model predicts that inclusions located in an area of high circumferential stress (>300 kPa) in the cap can intensify this stress to nearly 600 kPa when the cap thickness is <65 microm. The most likely candidates for the inclusions are either calcified macrophages or smooth muscle cells that have undergone apoptosis.

Insights into the pathophysiology of ST-elevation myocardial infarction

Although an approximate 13 million individuals in the United States are known to have coronary artery disease (CAD), only a small percentage of them develop unstable CAD each year. About 500,000 to 1 million people present annually with an ST-elevation myocardial infarction (STEMI), some of whom had never been diagnosed with CAD. The known etiology of coronary occlusion is the disruption of the atherosclerotic plaque within the vascular wall, and vascular inflammation is thought to lead to this disruption. Since many patients with CAD never suffer an myocardial infarction, the question then becomes why does inflammation-induced plaque disruption occur in only some patients? The explanation may lie in differing genetic and phenotypic characteristics. A greater understanding of the pathophysiology and the identification of new genetic and inflammatory markers are slowly leading to new therapeutic interventions that promise to greatly reduce the morbidity and mortality associated with CAD within the foreseeable future.

Pathology of the thin-cap fibroatheroma: a type of vulnerable plaque

Thin cap atheroma is the precursor of plaque rupture, which accounts for a majority of coronary thrombi. The morphologic features of thin cap atheromas that predict rupture are unknown, but we know from studies of ruptured plaques that large necrotic cores, fibrous cap < 65 microns and numerous macrophages within the cap likely indicate instability. There is some evidence that a speckled pattern of calcification is associated with vulnerability to rupture. There are usually multiple thin cap atheroma in the hearts of patients dying with acute plaque rupture, as well as multiple fibroatheromas with intraplaque hemorrhage. Targeted therapy for the purpose of stabilizing coronary lesions that are prone to rupture is a major future goal of the interventionist.

Vulnerable plaque: the pathology of unstable coronary lesions

Vulnerable plaques have been defined as precursors to lesions that rupture. However, coronary thrombosis may occur from other lesions like plaque erosion and calcified nodules, although to a lesser frequency than rupture. Therefore, the definition of vulnerable plaque should be all-inclusive. Using descriptive terminology, the authors define the precursor lesion of plaque rupture as "thin-cap fibroatheroma" (TCFA). Morphologically, TCFAs have a necrotic core with an overlying thin fibrous cap (< 65 mm) consisting of collagen type I, which is infiltrated by macrophages. These lesions are most frequent in the coronary tree of patients dying with acute myocardial infarction and least common in those with plaque erosion. TCFAs are more common in patients with high serum total cholesterol (TC) and a high TC to high density cholesterol ratio, in women > 50 years, and in those patients with elevated levels of high sensitivity C-reactive protein. TCFAs are mostly found in the proximal left anterior descending coronary arteries and less commonly in the proximal right or the proximal left circumflex coronary arteries. In TCFAs, necrotic core length is approximately 2-17 mm (mean 8 mm) and the underlying cross-sectional luminal narrowing in over 75% of cases is < 75% (< 50% diameter stenosis). The area of the necrotic core in at least 75% of cases is < or = 3 mm2. Clinical studies of TCFAs are limited as angiography and intravascular ultrasound (IVUS) catheters cannot precisely identify these lesions. Newer catheters and other techniques are at various stages of development and will play a significant role in the understanding of plaque progression and the development of symptomatic coronary artery disease.

Update on cardiovascular disease in post-menopausal women

Cardiovascular disease (CVD), and in particular coronary artery heart disease (CAHD), is the leading cause of morbidity and mortality in women. Until recently, most of our knowledge about the pathophysiology of CVD in women - and, subsequently, management guidelines - were based on studies conducted mostly in men. While similar mechanisms operate to induce CVD in women and men, gender-related differences exist in the anatomy and physiology of the myocardium, and sex hormones modify the course of disease in women. Women, more than men, have their initial manifestation of CAHD as angina pectoris; are likely to be referred for diagnostic tests at a more advanced stage of disease, and are less likely than men to have corrective invasive procedures. The overall morbidity and mortality following the initial ischaemic heart event is worse in women, and the case fatality rate is greater in women than in men. Also, the relative impact of impaired vasoreactivity of the coronary artery, increased viscosity of the blood and dysregulation of automaticity and arrhythmia, is greater in women than in men. The most effective means of decreasing the impact of CVD on women's health is by an active approach from childhood to proper principles of healthcare in order to modify the contribution of specific risk factors. The latter include obesity, abnormal plasma lipid profile, hypertension, diabetes mellitus, cigarette smoking, sedentary lifestyle, increased blood viscosity, augmented platelet aggregability, stress and autonomic imbalance. The use of lipid-lowering drugs has not been adequately studied in women but reports from studies conducted mostly in men do predict an advantage also to women. Oestrogen deficiency after spontaneous or medically induced menopause is an important risk factor for CVD and CAHD. Observational and mechanistic data suggest a role for oestrogen replacement after menopause for primary, and possibly secondary, prevention of CVD. However, two recent prospective trials suggest that treatment de novo with hormone replacement of older post-menopausal women after an acute coronary event may not confer cardiovascular protection and may increase the risk of thromboembolic disease. Results of ongoing long-term studies may determine the beneficial role of hormone replacement versus potential risks involved with this treatment.

Triggers of acute coronary syndromes

Despite recent progress in prevention of coronary heart disease, approximately 50% of the deaths from coronary artery disease continue to occur out of hospital, and many major cardiac events occur in individuals not previously known to be at risk. These facts create the need to identify the acute causes of myocardial infarction (MI) and sudden death, which has led to a rapid growth in interest over the last 15 years in the field of triggering research. Since initial observations that the incidence of MI onset was time and activity dependent with circadian, circaseptan, and circannual variation, triggering of MI by heavy exertion, sexual activity, anger, mental stress, cocaine and marijuana use, and exposure to air pollution has been demonstrated. Study of the pathophysiological changes produced by these triggers may provide novel therapeutic and preventive targets by a more thorough understanding of vulnerable plaque disruption and coronary thrombosis.

The reperfusion era. Strategies for establishing or maintaining coronary patency

Only 3 decades ago, controversy existed over the origin of the thrombus that occluded coronary arteries during myocardial infarction (MI). Then, the acute clinical angiographic studies of DeWood butterssed new pathological and experimental evidence that the thrombus was the proximate cause of MI and unstable angina. The remaining years of the 20th century saw an explosion of knowledge delineating a spectrum of related disorders now collectively called acute coronary syndromes (ACS). The clinician managing patients is confronted with an array of evidence as more than 75,000 patients worldwide have been randomized to clinical trials in ACS. This article reviews key pathophysiological concepts, presents an initial strategy for triage of patients, and summarizes evidence-based medicine guiding therapy for acute coronary lesions.

Inflammatory pathways in atherosclerosis and acute coronary syndromes

Evidence from a broad range of studies demonstrates that atherosclerosis is a chronic disease that, from its origins to its ultimate complications, involves inflammatory cells (T cells, monocytes, macrophages), inflammatory proteins (cytokines, chemokines), and inflammatory responses from vascular cells (endothelial cell expression of adhesion molecules). Investigators have identified a variety of proteins whose levels might predict cardiovascular risk. Of these candidates, C-reactive protein, tumor necrosis factor-alpha, and interleukin-6 have been most widely studied. There is also the prospect of inflammation as a therapeutic target, with investigators currently debating to what extent the decrease in cardiovascular risk seen with statins, angiotensin-converting enzyme inhibitors, and peroxisome proliferator-activated receptor ligands derives from changes in inflammatory parameters. These advances in basic and clinical science have placed us on a threshold of a new era in cardiovascular medicine.

Clinical management of patients with coronary syndromes and negative fractional flow reserve findings

AIMS

New interventional techniques to diagnose coronary artery stenosis, such as calculation of myocardial fractional flow reserve (FFR) with a guidewire and pressure transducer, provide a functional assessment of coronary lesions. The present study was designed to investigate the occurrence of cardiac events in patients with coronary syndromes and negative FFR findings in moderately severe coronary stenosis in order to determine the usefulness of this technique in predicting coronary events during follow-up for problems commonly encountered in clinical practice. A further objective was to evaluate the safety of deferring angioplasty in patients with a negative FFR result.

METHODS

We studied 43 patients with 44 moderately severe coronary artery stenoses on angiography and FFR > or = 0.75. Mean age of the patients was 58 +/- 11.4 years. The indications for coronary angiography included recent unstable angina in 24 (55.8%) patients, recent acute myocardial infarction in 10 (23.2%) patients, 5 (11.6%) patients with a coronary stent who had symptoms of uncertain cause, and stable angina in 4 (9.3%) patients.

RESULTS

During a mean follow-up period of 10.7 +/- 5.9 months, clinical events (unstable angina) occurred in five patients. In three patients, the initially investigated artery was involved, and in the two patients who required coronary revascularization, unstable angina was related with an artery different from the one studied initially.

CONCLUSIONS

Patients with recent coronary syndromes and negative FFR findings in moderately severe coronary stenosis were unlikely to have cardiac events during a 10-month follow-up period. Our findings suggest that FFR is a potentially useful indicator of the likelihood of cardiac events and thus represents a useful aid in clinical decision-making in the hemodynamics laboratory. This diagnostic technique also is potentially useful in identifying patients for whom angioplasty can be safely deferred.

Lipid-lowering therapy after coronary revascularization

Atherosclerosis is often asymptomatic, unrecognized, and undertreated. Lumen irregularities are important angiographic findings that should be addressed aggressively through risk factor modification, medical therapy, and coronary revascularization. Both angiographic and clinical benefits have been demonstrated with lipid reduction therapy in randomized clinical trials. Coronary revascularization is indicated for symptom relief and improvement in quality of life in patients with acute coronary syndromes at "intermediate" and "high" risk of subsequent death or myocardial infarction. In patients following percutaneous coronary intervention (PCI), future cardiac events may be related to lumen renarrowing or to progression of atherosclerotic disease at sites remote from the site of coronary revascularization. The time course of restenosis is relatively self-limiting, generally occurring within 6-12 months after the procedure. Clinical events occurring > 1 year after PCI generally relate to new lesions or progression of existing atherosclerotic disease. Patients with diabetes mellitus may be at higher risk for late coronary events than nondiabetic patients. In post-coronary artery bypass surgery (CABG) patients, the majority of late events relate to degeneration of saphenous vein grafts. Lipid lowering therapy after coronary revascularization has been shown to prevent clinical events related to plaque instability and inhibit progression of saphenous vein graft disease. Thus, there are 2 goals in management of patients with symptomatic coronary artery disease: (1) to relieve the flow-limiting stenosis, and (2) to prevent future clinical events with aggressive lipid lowering and modification of other risk factors. Patients, specialists, and primary care physicians each need to take accountability for this risk-factor modification.

Integrated evaluation of relation between coronary lesion features and stress echocardiography results: the importance of coronary lesion morphology

OBJECTIVES

The aim of this study was to analyze, in the same group of patients, the relationship between multiple variables of coronary lesion and results of exercise, dobutamine and dipyridamole stress echocardiography tests.

BACKGROUND

Integrated evaluation of the relation between stress echocardiography results and angiographic variables should include not only the assessment of stenosis severity but also evaluation of other quantitative and qualitative features of coronary stenosis.

METHODS

Study population consisted of 168 (138 male, 30 female, mean age 51+/-9 years) patients, on whom exercise (Bruce treadmill protocol), dobutamine (up to 40 mcg/kg/min) and dipyridamole (0.84 mg/kg over 10 min) stress echocardiography tests were performed. Stress echocardiography test was considered positive for myocardial ischemia when a new wall motion abnormality was observed. One-vessel coronary stenosis ranging from mild stenosis to complete obstruction of the vessel was present in 153 patients, and 15 patients had normal coronary arteries. The observed angiographic variables included particular coronary vessel, stenosis location, the presence of collaterals, plaque morphology according to Ambrose classification, percent diameter stenosis and obstruction diameter as assessed by quantitative coronary arteriography.

RESULTS

Covariates significantly associated with the results of physical and pharmacological stress tests included for all three stress modalities presence of collateral circulation, percent diameter stenosis and obstruction diameter, as well as lesion morphology (p < 0.05 for all, except collaterals for dobutamine stress test, p = 0.06). By stepwise multiple logistic regression analysis, the strongest predictor of the outcome of exercise echocardiography test was only percent diameter stenosis (p = 0.0002). However, both dobutamine and particularly dipyridamole stress echocardiography results were associated not only with stenosis severity - percent diameter stenosis (dobutamine, p = 0.04; dipyridamole, p = 0.003) - but also, and even more strongly, with lesion morphology (dobutamine, p = 0.006; dipyridamole, p = 0.0009). As all of stress echocardiography results were significantly associated with percent diameter stenosis, the best angiographic cutoff in relation to the results of stress echocardiography test was: exercise, 54%; dobutamine, 58% and dipyridamole, 60% (p < 0.05 vs. exercise).

CONCLUSIONS

Integrated evaluation of angiographic variables have shown that the results of dobutamine and dipyridamole stress echocardiography are not only influenced by stenosis severity but also, and even more importantly, by plaque morphology. The results of exercise stress echocardiography, although separately influenced by plaque morphology, are predominantly influenced by stenosis severity, due to a stronger exercise capacity in provoking myocardial ischemia in milder forms of coronary stenosis.

Myocardial infarction and percent arteriographic stenosis of culprit lesion: report from the Program on the Surgical Control of the Hyperlipidemias (POSCH)

The objective of this study was to assess the percent stenosis of the culprit lesion responsible for subsequent myocardial infarction in the Program on the Surgical Control of the Hyperlipidemias (POSCH). It is unknown if the susceptible coronary artery culprit lesion responsible for an acute myocardial infarction is relatively large ( > or = 50% arteriographic stenosis) and hemodynamically significant ( > or = 70% stenosis), or small ( < 50%, stenosis) and asymptomatic. Certain necropsy and arteriography studies support the large progenitor lesion concept, and other arteriography studies support the small lesion hypothesis. We analyzed the coronary arteriogram immediately preceding a Q wave (transmural) myocardial infarction for the degree of stenosis of the suspected culprit lesion, which was selected by visual inspection of the coronary circulation supplying the electrocardiogram-defined area of myocardial infarction. There was no perceptible difference with respect to vessel segment distribution of culprit lesions or time to infarction between the 52 control-group patients and the 27 intervention-group patients. For the two groups combined (n=79), the predominantly involved segments were the middle right coronary artery and the proximal left anterior descending coronary artery. The time interval from the preceding coronary arteriogram closest to the index myocardial infarction ranged from 0 days to 10 years; however, 64.6% of the arteriograms were performed 2 years or less prior to the myocardial infarction. Only 5.1% of the patients in both groups combined had a culprit lesion stenosis < 50%, while 88.6% of the patients in both groups combined had a culprit lesion stenosis > or = 70%. The results strongly favor the large lesion hypothesis of causation for myocardial infarction. It is premature, however, to state that the relative size of the culprit lesion has been indisputably determined. The resolution of this problem has exceedingly important practical implications for the management of patients with known atherosclerotic coronary heart disease and for those asymptomatic individuals with silent atherosclerotic coronary heart disease.

Pravastatin has cholesterol-lowering independent effects on the artery wall of atherosclerotic monkeys

OBJECTIVES

This study examined the direct effects of pravastatin on the artery wall of atherosclerotic monkeys after dietary lipid lowering.

BACKGROUND

Clinical trials suggest that hepatic hydroxymethylglutaryl coenzyme A reductase inhibitors may reduce the risk of coronary heart disease out of proportion to their effect on angiographically assessed lumen stenosis.

METHODS

Thirty-two cynomolgus monkeys were fed an atherogenic diet for 2 years (progression phase) and then fed a lipid-lowering diet either containing (n = 14) or not containing (n = 18) pravastatin in the diet for an additional 2 years (treatment phase). As designed, total plasma cholesterol and high density lipoprotein concentrations did not differ between groups at the beginning of or during the treatment phase of the experiment (p > 0.05).

RESULTS

Quantitative angiography revealed that coronary arteries of the pravastatin-treated monkeys dilated 10 +/- 3%, whereas those from untreated control monkeys constricted -2 +/- 2% in response to acetylcholine (p < 0.05). There were no treatment effects on plaque size of coronary arteries measured at the end of the treatment phase of the study (0.110 +/- 0.048 mm2 [untreated] vs. 0.125 +/- 0.051 mm2 [pravastatin]; p > 0.05) or on the amount of reduction in plaque size in common iliac arteries during the treatment phase of the study (48 +/- 5% [untreated] vs. 45 +/- 6% [pravastatin]; p > 0.05). However, histochemical analysis of the atherosclerotic lesions indicated that the arteries from pravastatin-treated monkeys had significantly fewer macrophages in the intima and media, less calcification and less neovascularization in the intima (p < 0.05).

CONCLUSIONS

We conclude that compared with control monkeys, the arteries of pravastatin-treated monkeys had better dilator function and plaque characteristics more consistent with plaque stability than those of monkeys not receiving pravastatin. These beneficial arterial effects of pravastatin occurred independently of plasma lipoprotein concentrations and despite similar changes in plaque size between the groups.

Evaluation of chest pain in the emergency department

The evaluation of chest pain in the emergency setting should be systematic, risk based, and goal driven. An effective program must be able to evaluate all patients with equal thoroughness under the assumption that any patient with chest pain could potentially be having an MI. The initial evaluation is based on the history, a focused physical examination, and the ECG. This information is sufficient to categorize patients into groups at high, moderate, and low risk. Table 14 is a template for a comprehensive chest-pain evaluation program. Patients at high risk need rapid initiation of appropriate therapy: thrombolytics or primary angioplasty for the patients with MIs or aspirin/heparin for the patients with unstable angina. Patients at moderate risk need to have an acute coronary syndrome ruled in or out expediently and additional comorbidities addressed before discharge. Patients at low risk also need to be evaluated, and once the likelihood of an unstable acute coronary syndrome is eliminated, they can be discharged with further evaluation performed as outpatients. Subsequent evaluation should attempt to assign a definitive diagnosis while also addressing issues specific to risk reduction, such as cholesterol lowering and smoking cessation. It is well documented that 4% to 5% of patients with MIs are inadvertently missed during the initial evaluation. This number is surprisingly consistent among many studies using various protocols and suggests that an initial evaluation limited to the history, physical examination, and ECG will fail to identify the small number of these patients who otherwise appear at low risk. The solution is to improve the sensitivity of the evaluation process to identify these patients. It appears that more than simple observation is required, and at the present time, no simple laboratory test can meet this need. However, success has been reported with a number of strategies including emergency imaging with either radionuclides such as sestamibi or echocardiography. Early provocative testing, either stress or pharmaceutic, may also be effective. The added value of these tests is only in their use as part of a systematic protocol for the evaluation of all patients with acute chest pain. The initial evaluation of the patient with chest pain should always consider cardiac ischemia as the cause, even in those with more atypical symptoms in whom a cardiac origin is considered less likely. The explicit goals for the evaluation of acute chest pain should be to reduce the time to treat MIs and to reduce the inadvertent discharge of patients with occult acute coronary syndromes. All physicians should become familiar with appropriate risk stratification of patients with acute chest pain. Systematic strategies must be in place to assure rapid and consistent identification of all patients and the expedient initiation of treatment for those patients with acute coronary syndromes. These strategies should include additional methods of identifying acute coronary syndromes in patients initially appearing as at moderate or low risk to assure that no unstable patients are discharged. All patients should be followed up closely until the cardiovascular evaluation is completed and, when possible, a definitive diagnosis is determined. Finally, this must be done efficiently, cost-effectively, and in a manner that will result in an overall improvement in patient care.

Role of plaque size and degree of stenosis in acute myocardial infarction

Angiographically apparent coronary artery stenoses limit coronary flow, produce symptomatic ischemia, and can be targeted for revascularization. Severe stenoses are more likely to occlude than segments without significant stenoses. Coronary angiography underestimates the extent of coronary atherosclerosis. Arterial segments without severe stenoses are much more common, and their risk of occlusion is not zero. Thus, the majority of myocardial infarctions are due to occlusion of arteries that do not contain obstructive coronary stenoses. Consequently, coronary angiography is not able to accurately predict the site of a coronary artery occlusion that subsequently will produce myocardial infarction.

Clinical perspectives on primary and secondary prevention of coronary atherosclerosis

Several clinical trials have provided compelling evidence in support of the benefits of lipid-lowering therapy for primary and secondary prevention of atherosclerosis. The results of primary prevention trials have demonstrated that coronary morbidity can be reduced and survival improved with effective lipid-lowering regimens. There has been concern, however, regarding harmful effects (e.g., increased rate of suicide and increased risk of gastrointestinal cancer) of cholesterol-lowering therapies in primary prevention trials. These concerns are not well supported by strong evidence, and there has been lack of a dose-response relationship. It is generally believed that for 1% reduction in serum cholesterol, there is a 2% reduction in the risk of coronary events. The results of numerous secondary prevention trials have clearly demonstrated the benefit of lipid-lowering therapies in reducing the risk of future cardiac events and cardiac mortality in patients with preexistent coronary artery disease. Several studies have shown that treatment regimens effective in reducing LDL cholesterol levels lead to regression of atherosclerotic plaques as well as retard the progression of the disease process. Interestingly, some of these studies have also shown that when measured angiographically, the luminal diameter at the site of stenotic lesions might improve only by an average of 2% to 3%; however, this small degree of improvement is associated with a remarkable reduction by 35% to 25% in the risk of future coronary events. These findings further corroborate the hypothesis about the importance of a lipid-rich cap of the vulnerable plaques and suggest that the reduction in lipid levels is associated with the efflux of lipids from the plaque, thus converting it from a vulnerable to a stable state. The most recent data from the 4S trial have unequivocally demonstrated the benefits of treatment with HMG coenzyme-A reductase inhibitors in reducing the risk of future coronary events and improving the overall survival in patients with established CHD. Although there is still ongoing controversy regarding the precise course of action for primary prevention of CHD, the results of a large number of studies provide overwhelming evidence in support of aggressive lipid-lowering therapy for secondary prevention of CHD. Based on the findings of these studies, it seems prudent that clinicians become actively involved in the evaluation and management of lipid abnormalities and other risk factors in patients with CHD.

Atherosclerosis, oxidative stress, and antioxidant protection in endothelium-derived relaxing factor action

The vascular endothelium plays a central role in the regulation of vascular function. In particular, the local release of endothelium-derived relaxing factor (EDRF) regulates vascular tone and prevents platelet adhesion to the vascular wall. Impairment of EDRF action develops early in atherosclerosis and, in part, contributes to platelet deposition and vasospasm involved in the clinical expression of coronary artery disease. Recent evidence suggests that an imbalance between vascular oxidative stress and antioxidant protection is involved in the development of this vascular dysfunction. In this report, the relation between oxidative stress, atherosclerosis, and abnormal EDRF action is reviewed with particular attention to the effects of antioxidant supplementation in animal models of atherosclerosis and hypercholesterolemia.

Acute ischemic syndromes

The diagnosis and treatment of patients with acute manifestations of ischemic heart disease are major public health issues. This article reviews the current state of knowledge about the problem of acute ischemic syndromes, the events leading to clinical manifestations, the key elements of the diagnosis, the therapies that can affect outcome, and the organization of systems to deal with this problem in a cost-effective manner.

Acute myocardial infarction--the angiographic picture: new insights into the pathogenesis of myocardial infarction

The angiographic appearance of the coronary arteries were examined in 302 patients with stable angina pectoris and compared to 308 patients with acute myocardial infarction, who received high-dose intravenous thrombolytic therapy, in order to elucidate the underlying angiopathological picture in the two diseases. In each group coronary lesions were present in proximal segments of the arteries and were closely related to bifurcations. Lesions were more extensively distributed in the coronary tree in patients with stable angina and they had an average of 5.4 lesions per patient, compared to the acute myocardial infarction group who had only 2.4 lesions. Also, in the acute myocardial infarction patients, four-fifths of the culprit arteries were patent, 104 (34%) had a ruptured plaque, 22 (7%) had an ulcerated plaque and in 190 (62%) the lesions were eccentric. The study shows that patients with myocardial infarction who are suitable for thrombolysis have a unique coronary angiographic picture and the acute episode is caused by sudden rupture of a localized atheromatous plaque which initiates an obstructive thrombotic cascade.

Comparison of patients with < 60% to > or = 60% diameter narrowing of the myocardial infarct-related artery after thrombolysis. The TIMI Investigators

The purpose of this study was to analyze angiographic findings, clinical course, and follow-up data on 1,752 patients who underwent protocol cardiac catheterization 18 to 48 hours after enrollment in the Thrombolysis in Myocardial Infarction (TIMI) II pilot and randomized trial: 244 patients (14.0%) had < 60% diameter stenosis in the infarct-related artery and TIMI grade 2 or 3 flow, 1,249 (71.2%) had a narrowing > or = 60% in diameter with TIMI grade 2 or 3 flow, and 259 patients (15%) had TIMI grade 0 or 1 flow (total occlusion). Patients with < 60% narrowing in the infarct-related artery were younger (p < 0.001) and more likely to be current smokers than those with more severe narrowings (p < 0.003). Patients with < 60% diameter stenosis in the infarct-related artery were more likely to have a predischarge radionuclide ejection fraction > 55% (p < 0.001) than were other patient groups. The 1-year mortality rate of patients with < 60% diameter stenosis in the infarct-related artery was 1.6% compared with 4.4% for patients with stenosis > or = 60% and TIMI grade 2 or 3 flow (p = 0.05) and 7.0% for patients with total occlusion (p = 0.004). Patients with stenosis < 60% in the infarct-related artery 18 to 48 hours after thrombolytic therapy have a good prognosis. Infarct artery status predicts predischarge ejection fraction and 1-year mortality.