Diagnostic and prognostic value of non-invasive imaging in known or suspected coronary artery disease

Emerging role of positron emission tomography (PET) imaging in cardiac surgery

Historically, structural and anatomical imaging has been the mainstay in the diagnosis and management of cardiovascular diseases. In recent years there has been a shift toward increased use of functional imaging studies, including positron emission tomography (PET). PET is a noninvasive nuclear medicine-imaging technique that uses radiotracers to generate images of a radionucleotide distribution by detecting the physiologic substrates that emit positron radionuclides. This article will focus on the applications of PET imaging for the cardiac surgeon and highlight the collaborative nature of using PET imaging for the management of complex heart disease. We present cases that demonstrate the value of using PET imaging in the diagnosis of coronary artery disease and management of complex endocarditis, and in targeted cardiovascular therapies.

Automatic Diagnosis of Coronary Artery Disease in SPECT Myocardial Perfusion Imaging Employing Deep Learning

Focusing on coronary artery disease (CAD) patients, this research paper addresses the problem of automatic diagnosis of ischemia or infarction using single-photon emission computed tomography (SPECT) (Siemens Symbia S Series) myocardial perfusion imaging (MPI) scans and investigates the capabilities of deep learning and convolutional neural networks. Considering the wide applicability of deep learning in medical image classification, a robust CNN model whose architecture was previously determined in nuclear image analysis is introduced to recognize myocardial perfusion images by extracting the insightful features of an image and use them to classify it correctly. In addition, a deep learning classification approach using transfer learning is implemented to classify cardiovascular images as normal or abnormal (ischemia or infarction) from SPECT MPI scans. The present work is differentiated from other studies in nuclear cardiology as it utilizes SPECT MPI images. To address the two-class classification problem of CAD diagnosis, achieving adequate accuracy, simple, fast and efficient CNN architectures were built based on a CNN exploration process. They were then employed to identify the category of CAD diagnosis, presenting its generalization capabilities. The results revealed that the applied methods are sufficiently accurate and able to differentiate the infarction or ischemia from healthy patients (overall classification accuracy = 93.47% ± 2.81%, AUC score = 0.936). To strengthen the findings of this study, the proposed deep learning approaches were compared with other popular state-of-the-art CNN architectures for the specific dataset. The prediction results show the efficacy of new deep learning architecture applied for CAD diagnosis using SPECT MPI scans over the existing ones in nuclear medicine.

Diagnostic efficiency of quantification of myocardial blood flow and coronary flow reserve with CZT dynamic SPECT imaging for patients with suspected coronary artery disease: a comparative study with traditional semi-quantitative evaluation

Background

Myocardial blood flow (MBF) quantitation with cadmium-zinc-telluride (CZT) dynamic single-photon emission computed tomography (SPECT) is being increasingly investigated toward clinical utilization.

Methods

In this prospective study, forty-nine patients with suspected or known coronary artery disease (CAD) underwent a rest/adenosine triphosphate (ATP) stress dynamic and routine gated myocardial perfusion imaging (MPI) by CZT SPECT and then received coronary angiography (CAG). Quantitative diagnosis from the dynamic SPECT and a flow diagram was automatically obtained by the dedicated software and compared with the result of semi-quantitative analysis with gated MPI using the angiographic stenosis as the reference standard.

Results

When stenosis ≥50% was considered at the participant level, the sensitivity (SN), specificity (SP), positive predictive value (PPV), negative predictive value (NPV) and accuracy (AC) of the quantitative diagnosis were higher than semi-quantitative method as (84.4% vs. 65.6%, 88.2% vs. 70.6%, 93.1% vs. 80.8%, 75.0% vs. 52.2%, 85.7% vs. 67.3%) (all P<0.05). The receiver operating characteristic (ROC) curve analysis generated the optimal critical value as 1.86 and 1.61 mL/min/g for stress MBF (sMBF) and MFR, respectively. The diagnosis performance of the quantitative diagnosis was higher than semi-quantitative method as (78.9% vs. 68.4%, 63.3% vs. 60.0%, 57.7% vs. 52.0%, 82.6% vs. 75.0%, 69.4% vs. 63.3%) for the criteria of ≥75% stenosis on CAG (all P<0.05) with optimal critical values as 1.71 and 1.15 mL/min/g. There was no significant difference between sMBF and MFR.

Conclusions

The diagnostic efficiency by using the quantitative method of CZT dynamic SPECT imaging is superior to traditional semi-quantitative gated MPI for the diagnosis of CAD, which improved the diagnostic specificity and accuracy when the critical was stenosis ≥50%.

Nuclear investigative techniques and their interpretation in the heart and vascular disease

Over the last several decades, myocardial perfusion imaging with single photon emission tomography and positron emission tomography has been a mainstay for the evaluation of patients with known or suspected coronary artery disease non-invasively. Technical advances in imaging modalities and radiopharmaceutical have revolutionaries the understanding of pathogenesis and management of various diseases. In this article, we shall discuss the various available imaging nuclear medicine techniques, radiopharmaceutical, and common indications. In the era of “precision medicine,” imaging has to be patient centered. We will briefly review the upcoming areas of nuclear medicine imaging apart from perfusion imaging, such as advances in myocardial blood flow quantitation and molecular imaging.

Plasma soluble C-type lectin-like receptor-2 is associated with the risk of coronary artery disease

Accumulating evidence suggests that C-type lectin-like receptor-2 (CLEC-2) plays an important role in atherothrombosis. In this case-control study, we investigated the association between CLEC-2 and incidence of coronary artery disease (CAD). A total of 216 patients, including 14 cases of stable angina pectoris (SAP, non-ACS) and 202 cases of acute coronary syndrome (ACS), and 89 non-CAD control subjects were enrolled. Plasma levels of soluble CLEC-2 (sCLEC-2) were measured using the enzyme-linked immunosorbent assay (ELISA). Compared with the control group (65.69 (55.36-143.22) pg/mL), the plasma levels of sCLEC-2 were significantly increased in patients with CAD (133.67 (88.76-220.09) pg/mL) and ACS (134.16 (88.88-225.81) pg/mL). The multivariate adjusted odds ratios (95% confidence interval) of CAD reached 2.01 (1.52-2.66) (P_trend < 0.001) for each 1-quartile increase in sCLEC-2. Restricted cubic splines showed a positive dose-response association between sCLEC2 and CAD incidence (P_linearity < 0.001). The addition of sCLEC-2 to conventional risk factors improved the C statistic (0.821 vs. 0.761, P = 0.004) and reclassification ability (net reclassification improvement: 57.45%, P < 0.001; integrated discrimination improvement: 8.27%, P < 0.001) for CAD. In conclusion, high plasma sCLEC-2 is independently associated with CAD risk, and the prognostic value of sCLEC-2 may be evaluated in future prospective studies.

Multimodality imaging in ischaemic heart failure

In heart failure, extensive evaluation with modern non-invasive imaging modalities is needed to assess causes, pathophysiology, and haemodynamics, to determine prognosis and consider therapeutic options. This systematic evaluation includes a stepwise assessment of left ventricular size and function, the presence and severity of coronary artery disease, mitral regurgitation, pulmonary hypertension, right ventricular dilation and dysfunction, and tricuspid regurgitation. Based on this imaging-derived information, the need for specific therapies besides optimised medical therapy can be determined. The need for revascularisation, implantation of an implantable cardiac defibrillator, and mitral or tricuspid valve repair or replacement, can be (partially) guided by non-invasive imaging. Importantly, randomised controlled trials on the use of non-inasive imaging to guide therapy are scarce in this field and most non-pharmacological therapies are based on expert-consensus, but whenever trials are available, they will be addressed in this paper.

Myocardial Perfusion Imaging: A Brief Review of Nuclear and Nonnuclear Techniques and Comparative Evaluation of Recent Advances

Coronary artery disease (CAD) is the leading cause of morbidity and mortality worldwide. Invasive coronary angiography (ICA) is the gold standard for the evaluation of epicardial CAD. In the pathogenesis of the CAD, myocardial perfusion abnormalities are the first changes that appear followed by wall motion abnormalities, electrocardiogram changes, and angina. Myocardial perfusion imaging (MPI) demonstrates the cumulative effect of pathology at epicardial coronary arteries, small vessels, and endothelium. Thus, it evaluates the overall burden of ischemic heart disease (IHD). MPI is used noninvasively to diagnose early asymptomatic CAD or to know the functional significance of known CAD. There are evidence that early detection of myocardial perfusion abnormalities followed by aggressive intervention against cardiovascular risk factors may restore myocardial perfusion. This may lead to reduce morbidity and mortality. Various MPI modalities have been used to diagnose and define the severity of CAD. Cardiac myocardial perfusion single-photon emission computed tomography (myocardial perfusion scintigraphy [MPS]) has been in use since decades. Several newer modalities such as positron emission tomography, cardiac magnetic resonance imaging, computed tomography perfusion, and myocardial contrast echocardiography are developing utilizing the similar principle of MPS. We shall be reviewing briefly these modalities, their performance, comparison to each other, and with ICA.

New solid state cadmium-zinc-telluride technology for cardiac single photon emission computed tomographic myocardial perfusion imaging

INTRODUCTION

Single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is well established as diagnostic test for patients with suspected or known coronary artery disease. New camera systems have been developed with cadmium-zinc-telluride (CZT) detectors, novel collimator designs and reconstruction software. Areas covered: We review the current state of cardiac SPECT, advances in conventional camera technology and the development and clinical validation of solid-state CZT cameras. Expert commentary: The development of CZT systems is timely and addresses current issues for clinical SPECT imaging. These systems have a significant increase in photon sensitivity, permitting much lower radiation patient doses at a time when the lay and medical communities are very concerned about the radiation doses resulting from medical imaging. The increased count sensitivity permits shorter acquisition times and greater patient throughput which may address the ongoing and increasing issue of decreased funding for healthcare and, particularly, diagnostic imaging. The improved image resolution should improve diagnostic accuracy and increase the value of SPECT imaging for management of patients with CAD at a time of significant competition from other imaging modalities.

Radionuclide myocardial perfusion imaging for the evaluation of patients with known or suspected coronary artery disease in the era of multimodality cardiovascular imaging

Over the last several decades, radionuclide myocardial perfusion imaging (MPI) with single photon emission tomography and positron emission tomography has been a mainstay for the evaluation of patients with known or suspected coronary artery disease (CAD). More recently, technical advances in separate and complementary imaging modalities including coronary computed tomography angiography, computed tomography perfusion, cardiac magnetic resonance imaging, and contrast stress echocardiography have expanded the toolbox of diagnostic testing for cardiac patients. While the growth of available technologies has heralded an exciting era of multimodality cardiovascular imaging, coordinated and dispassionate utilization of these techniques is needed to implement the right test for the right patient at the right time, a promise of "precision medicine." In this article, we review the maturing role of MPI in the current era of multimodality cardiovascular imaging, particularly in the context of recent advances in myocardial blood flow quantitation, and as applied to the evaluation of patients with known or suspected CAD.

Advances in the noninvasive evaluation of coronary artery disease with multislice computed tomography

Current noninvasive detection of coronary artery disease (CAD) is based on the demonstration of ischemia using stress-rest imaging, which is an indirect way of identifying CAD by demonstration of the hemodynamic consequences, rather than direct visualization of the obstructive lesions in the coronary arteries. Multislice computed tomography (MSCT) has recently emerged as an extremely rapidly developing noninvasive imaging modality, which allows anatomical imaging of the coronary arteries or noninvasive coronary angiography. In addition, total plaque burden, plaque morphology and (to some extent) plaque constitution can be assessed by MSCT. The technique also provides information on resting left ventricular systolic function, and possibly resting perfusion. Ideally, stress function and perfusion should also be evaluated, since this would allow detection of ischemia and would complete the picture of CAD. However, this is not routinely performed, since sequential acquisitions are associated with high radiation doses and thus pose a limitation for cardiovascular applications of MSCT. It is anticipated that, with a reduction in radiation, MSCT may become an important player in the diagnostic and prognostic work-up of patients with known or suspected CAD.

Rationale, design and methods of CTCA-PRORECAD (Computed Tomography Coronary Angiography Prognostic Registry for Coronary Artery Disease): a multicentre and multivendor registry

PURPOSE

This study was done to assess the prognostic value of computed tomography coronary angiography (CTCA) in a large multicentre population of patients with suspected coronary artery disease (CAD) and, in particular, its incremental value compared with traditional methods for risk stratification.

MATERIALS AND METHODS

This is a retrospective observational study that began in January 2003 conducted on patients with suspected CAD assessed with CTCA on the basis of symptoms (chest pain, dyspnoea) and/or abnormal or equivocal stress test and/or a high cardiovascular risk profile. The participating centres will provide data obtained with CTCA performed with 16-slice or higher equipment. Exclusion criteria are renal insufficiency, allergy to iodinated contrast material, pregnancy and previous myocardial infarction or revascularisation (percutaneous coronary intervention and/or coronary artery bypass graft). All patients are stratified by means of clinical assessment and/or data retrieved from a clinical database. Risk factors considered are hypertension, dyslipidaemia, diabetes mellitus, smoking, family history and obesity. Symptoms are classified as absent, typical chest pain, atypical chest pain and dyspnoea. Primary endpoints are death, major adverse cardiovascular events (cardiac death, unstable angina requiring hospitalisation, acute myocardial infarction) and shifting of cardiovascular risk category on the basis of coronary plaque burden. The secondary endpoint is coronary revascularisation. Telephone interviews and/or clinical databases are used for the follow-up. The study will be conducted on a population >1,000 patients.

CONCLUSIONS

The information collected from the Prognostic Registry for Coronary Artery Disease (PRORECAD) will provide insight into the prognostic value of CTCA in addition to demographic and clinical features. The results will allow for better use and interpretation of CTCA for prognostic purposes.

Stress echocardiography vs nuclear stress imaging in clinical cardiology

Stress echocardiography and nuclear stress imaging are important non-invasive tools in clinical cardiology. This review discusses the uses, strengths and limitations of these imaging modalities and looks at whether stress echocardiography can actually replace nuclear stress imaging.

Downstream procedures and outcomes after stress testing for chest pain without known coronary artery disease in the United States

BACKGROUND

Millions of Americans with suspected coronary artery disease undergo noninvasive cardiac stress testing annually. Downstream procedures and subsequent outcomes among symptomatic patients without known coronary disease referred for stress testing are not well characterized in contemporary community practice.

METHODS

We examined administrative insurance billing data from a national insurance provider from November 2004 through June 2007. After excluding patients with prior cardiac disease or chest pain evaluation, we identified 80,676 people age 40 to 64 years with outpatient cardiac stress testing within 30 days after an office visit for chest pain. We evaluated rates of invasive coronary angiography, coronary revascularization, and cardiovascular events after stress testing.

RESULTS

Within 60 days, only 8.8% of stress test patients underwent cardiac catheterization and only 2.7% underwent revascularization; within 1 year, only 0.5% died and had myocardial infarction or stroke. There were marked geographic variations in 1-year rates of catheterization (3.8%-14.8%) and revascularization (1.2%-3.0%) across 20 hospital referral regions.

CONCLUSIONS

In this large national cohort of middle-aged patients without previously coded cardiac diagnosis who were referred for stress testing after outpatient chest pain evaluation, few proceeded to invasive angiography or revascularization, and subsequent cardiovascular events were infrequent.

Combining dynamic and ECG-gated ⁸²Rb-PET for practical implementation in the clinic

OBJECTIVES

For many cardiac clinics, list-mode PET is impractical. Therefore, separate dynamic and ECG-gated acquisitions are needed to detect harmful stenoses, indicate affected coronary arteries, and estimate stenosis severity. However, physicians usually order gated studies only because of dose, time, and cost limitations. These gated studies are limited to detection. In an effort to remove these limitations, we developed a novel curve-fitting algorithm [incomplete data (ICD)] to accurately calculate coronary flow reserve (CFR) from a combined dynamic-ECG protocol of a length equal to a typical gated scan.

METHODS

We selected several retrospective dynamic studies to simulate shortened dynamic acquisitions of the combined protocol and compared (a) the accuracy of ICD and a nominal method in extrapolating the complete functional form of arterial input functions (AIFs); and (b) the accuracy of ICD and ICD-AP (ICD with a-posteriori knowledge of complete-data AIFs) in predicting CFRs.

RESULTS

According to the Akaike information criterion, AIFs predicted by ICD were more accurate than those predicted by the nominal method in 11 out of 12 studies. CFRs predicted by ICD and ICD-AP were similar to complete-data predictions (PICD=0.94 and PICD-AP=0.91) and had similar average errors (eICD=2.82% and eICD-AP=2.79%).

CONCLUSION

According to a nuclear cardiologist and an expert analyst of PET data, both ICD and ICD-AP predicted CFR values with sufficient accuracy for the clinic. Therefore, by using our method, physicians in cardiac clinics would have access to the necessary amount of information to differentiate between single-vessel and triple-vessel disease for treatment decision making.

Physiological assessment of myocardial perfusion using nuclear cardiology would enhance coronary artery disease patient care: which imaging modality is best for evaluation of myocardial ischemia? (SPECT-side)

Nuclear cardiology has played an important role in both diagnosis and risk assessments of coronary artery disease since early 1970. Among the non-invasive diagnostic tests, the great advantage of nuclear imaging is that this technique can obtain physiological information, such as myocardial perfusion, which is difficult to obtain by other techniques. When patients have inducible myocardial ischemia and sufficient viable myocardium, coronary revascularization treatment should be performed. Both stress myocardial perfusion imaging (MPI) and viability imaging provide important information. Another important aspect of stress perfusion imaging is that normal stress perfusion is associated with low risk for future cardiac events. Therefore, stress MPI plays an important role in the selection of an invasive therapeutic regime and also in avoiding unnecessary invasive procedures. As is the case for other imaging techniques, there have been many technical and instrumental developments in recent years in nuclear cardiology imaging, including new single-photon-emission computed tomography tracers, new pharmacological stress agents, a new generation of γ camera, and positron emission tomography. This review will address the advantages of nuclear cardiology in the clinical setting and recent developments in nuclear cardiology.

Cardiac magnetic resonance imaging: choice of the year: which imaging modality is best for evaluation of myocardial ischemia? (MRI-side)

The increasing variety of available cardiac imaging techniques have made the investigation of coronary artery disease more complex. On the one hand, nuclear cardiology or myocardial perfusion imaging (MPI) allows accurate and reliable quantitative measurement of myocardial blood flow. On the other hand, a newer technique, cardiac magnetic resonance imaging (CMR) is an attractive alternative for achieving similar purposes without exposing patients to radiation hazards. With a higher spatial resolution, CMR is more sensitive for detecting subendocardial ischemia; small myocardial infarction and/or fibrosis, which cannot be achieved in a nuclear study. Nuclear MPI has dominated clinical practice over the past 3 decades on the basis of an extensive amount of research. More upcoming research on CMR would warrant more evidence-based data of its value for disease diagnosis, prognosis and risk stratification and incorporating it into the clinical diagnostic and management algorithm.

Contractile reserve and extent of transmural necrosis in the setting of myocardial stunning: comparison at cardiac MR imaging

PURPOSE

To perform a comparison of cardiac magnetic resonance (MR) imaging-derived ejection fraction (EF) during low-dose dobutamine infusion (EF(D)) with the extent of segments with transmural necrosis in more than 50% of their wall thickness (ETN) for the prediction of major adverse cardiac events (MACEs) and late systolic recovery soon after a first ST-segment elevation myocardial infarction (STEMI).

MATERIALS AND METHODS

Institutional ethics committee approval and written informed consent were obtained. One hundred nineteen consecutive patients with a first STEMI, a depressed left ventricular EF, and an open infarct-related artery underwent MR imaging at 1 week after infarction. EF(D) and ETN (by using a 17-segment model) were determined, and the prediction of MACEs and systolic recovery at follow-up was assessed by using area under the receiver operating characteristic curve (AUC) and multivariable regression analysis.

RESULTS

During follow-up (median, 613 days; range, 312-1243 days), 18 MACEs (five cardiac deaths, six myocardial infarctions, seven readmissions for heart failure) occurred. MACEs were associated with a lower EF(D) (43% +/- 12 [standard deviation] vs 49% +/- 10, P = .02) and a larger ETN (seven segments +/- three vs four segments +/- three, P < .001). Patients with systolic recovery (increase in EF of >5% at follow-up compared with baseline EF, n = 44) displayed a higher EF(D) (51% +/- 10 vs 47% +/- 9, P = .04) and a smaller ETN (three segments +/- two vs five segments +/- three, P = .002) at 1 week. ETN and EF(D) both related to MACEs (AUC: 0.78 vs 0.67, respectively, P = .1) and systolic recovery (AUC: 0.68 vs 0.62, respectively, P = .3). According to multivariable analysis, ETN was the only MR variable associated with time to MACEs (hazard ratio, 1.38; 95% confidence interval: 1.19, 1.60; P < .001) and systolic recovery (odds ratio, 0.76; 95% confidence interval: 0.64, 0.92; P = .004) independent of baseline characteristics.

CONCLUSION

ETN is as useful as EF(D) for the prediction of MACEs and systolic recovery soon after STEMI.

Diagnostic accuracy of combined dipyridamole stress perfusion and delayed enhancement cardiovascular magnetic resonance imaging for detection of coronary artery disease

Background: The diagnosis of coronary artery disease (CAD) is one of the most common clinical issues that face medical practitioners. Myocardial ischemia can be noninvasively assessed with cardiovascular magnetic resonance imaging (CMRI), which has become an emerging modality. Objective: Determine the accuracy of dipyridamole stress CMRI by using stress and rest perfusion combined with delayed enhancement imaging for detecting CAD. Methods: Thirty-nine patients (24 men, 15 women; mean age 64±11.4 years) who had experienced prior myocardial infarction or had suspected CAD were enrolled. Dipyridamole stress CMRI with subsequent coronary angiography was performed within a mean time interval of 16 days (range: 1-30 days). The dipyridamole stress CMR protocol included stress and rest perfusion followed by delayed enhancement imaging. Per-vessel analysis was done according to 17-segment model recommendation by the American Heart Association. Results: Coronary angiography depicted significant coronary artery stenosis (>70% stenosis of major epicardial artery) in 26 patients (55 coronary arteries). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the combined stress and rest perfusion with delayed enhancement imaging for detection of significant coronary artery stenosis were 76-96%, 79-96%, 87-93%, 83-96%, and 85-95%, in left anterior descending, left circumflex, and right coronary arteries, respectively. Without delayed enhancement imaging, stress and rest perfusion produced slightly lower sensitivity (69-92%), specificity (73- 96%), positive predictive value (79-93%), negative predictive value (80-92%), and accuracy (79-92%). Conclusion: Dipyridamole stress CMRI combined with delayed enhancement imaging yielded high diagnostic accuracy for the detection of coronary artery disease. This modality allows the clinical application for detection of CAD in selected group of patients.

Quantitative imaging of coronary blood flow

Positron emission tomography (PET) is a nuclear medicine imaging modality based on the administration of a positron-emitting radiotracer, the imaging of the distribution and kinetics of the tracer, and the interpretation of the physiological events and their meaning with respect to health and disease. PET imaging was introduced in the 1970s and numerous advances in radiotracers and detection systems have enabled this modality to address a wide variety of clinical tasks, such as the detection of cancer, staging of Alzheimer's disease, and assessment of coronary artery disease (CAD). This review provides a description of the logic and the logistics of the processes required for PET imaging and a discussion of its use in guiding the treatment of CAD. Finally, we outline prospects and limitations of nanoparticles as agents for PET imaging.

Chronic coronary artery disease: diagnosis and management

Coronary artery disease (CAD) is the single most common cause of death in the developed world, responsible for about 1 in every 5 deaths. The morbidity, mortality, and socioeconomic importance of this disease make timely accurate diagnosis and cost-effective management of CAD of the utmost importance. This comprehensive review of the literature highlights key elements in the diagnosis, risk stratification, and management strategies of patients with chronic CAD. Relevant articles were identified by searching the PubMed database for the following terms: chronic coronary artery disease or stable angina. Novel imaging modalities, pharmacological treatment, and invasive (percutaneous and surgical) interventions have revolutionized the current treatment of patients with chronic CAD. Medical treatment remains the cornerstone of management, but revascularization continues to play an important role. In the current economic climate and with health care reform very much on the horizon, the issue of appropriate use of revascularization is important, and the indications for revascularization, in addition to the relative benefits and risks of a percutaneous vs a surgical approach, are discussed.

Prognostic value of a comprehensive cardiac magnetic resonance assessment soon after a first ST-segment elevation myocardial infarction

OBJECTIVES

To evaluate the prognostic value of a comprehensive cardiac magnetic resonance (CMR) assessment soon after a first ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

CMR allows for a simultaneous assessment of wall motion abnormalities (WMA), WMA with low-dose dobutamine (WMA-dobutamine), microvascular obstruction, and transmural necrosis. This approach has been proven to be useful to predict late systolic recovery soon after STEMI. Its prognostic value and the relative prognostic weight of these indexes are not well-defined.

METHODS

We studied 214 consecutive patients with a first STEMI treated with thrombolytic therapy or primary angioplasty discharged from hospital. In the first week (7 +/- 1 day after infarction), with CMR we determined the extent (number of segments) of WMA, WMA-dobutamine, microvascular obstruction, and transmural necrosis.

RESULTS

During a median follow-up of 553 days, 21 major adverse cardiac events (MACE) including 4 cardiac deaths, 6 nonfatal myocardial infarctions, and 11 readmissions for heart failure were documented. The MACE was associated with a larger extent of WMA (8 +/- 4 segments vs. 5 +/- 3 segments, p < 0.001), WMA-dobutamine (6 +/- 4 segments vs. 4 +/- 3 segments, p = 0.004), microvascular obstruction (3 +/- 3 segments vs. 1 +/- 2 segments p <0.001), and transmural necrosis (7 +/- 3 segments vs. 3 +/- 3 segments, p < 0.001). In a complete multivariate analysis that included baseline characteristics, electrocardiogram, biomarkers, angiography, ejection fraction, left ventricular volumes, and all CMR indexes, WMA/segment (hazard ratio: 1.29 [95% confidence interval: 1.11 to 1.49], p = 0.001) and the extent of transmural necrosis/segment (hazard ratio: 1.30 [95% confidence interval: 1.12 to 1.51], p < 0.001) were the only independent prognostic variables.

CONCLUSIONS

A comprehensive CMR assessment is useful for stratifying risk soon after STEMI, but only the extent of systolic dysfunction and of transmural necrosis provide independent prognostic information.

Nuclear imaging in heart failure

Heart failure is becoming the main clinical challenge in cardiology in the twenty-first century and is associated with high morbidity and mortality. Currently, several therapeutic options are available for heart failure patients, including medical therapy, revascularization, advanced cardiac surgery, device therapy, and cardiac transplantation. Future therapies are directed at cell and gene therapy. In this article the role of nuclear imaging in the management of heart failure patients is discussed.

ARFI imaging for noninvasive material characterization of atherosclerosis. Part II: toward in vivo characterization

Seventy percent of cardiovascular disease (CVD) deaths are attributed to atherosclerosis. Despite their clinical significance, nonstenotic atherosclerotic plaques are not effectively detected by conventional atherosclerosis imaging methods. Moreover, conventional imaging methods are insufficient for describing plaque composition, which is relevant to cardiovascular risk assessment. Atherosclerosis imaging technologies capable of improving plaque detection and stratifying cardiovascular risk are needed. Acoustic radiation force impulse (ARFI) ultrasound, a novel imaging method for noninvasively differentiating the mechanical properties of tissue, is demonstrated for in vivo detection of nonstenotic plaques and plaque material assessment in this pilot investigation. In vivo ARFI imaging was performed on four iliac arteries: (1) of a normocholesterolemic pig with no atherosclerosis as a control, (2) of a familial hypercholesterolemic pig with diffuse atherosclerosis, (3) of a normocholesterolemic pig fed a high-fat diet with early atherosclerotic plaques and (4) of a familial hypercholesterolemic pig with diffuse atherosclerosis and a small, minimally occlusive plaque. ARFI results were compared with spatially matched immunohistochemistry, showing correlations between elastin and collagen content and ARFI-derived peak displacement and recovery time parameters. Faster recoveries from ARFI-induced peak displacements and smaller peak displacements were observed in areas of higher elastin and collagen content. Importantly, spatial correlations between tissue content and ARFI results were consistent and observable in large and highly evolved as well as small plaques. ARFI imaging successfully distinguished nonstenotic plaques, while conventional B-mode ultrasound did not. This work validates the potential relevance of ARFI imaging as a noninvasive imaging technology for in vivo detection and material assessment of atherosclerotic plaques.

Cardiac radionuclide imaging in stable coronary artery disease and acute coronary syndromes

INTRODUCTION

The increasing number of available cardiac imaging techniques has made the investigation of coronary artery disease (CAD) more complex. Appropriate patient referral depends on an understanding of the pre-test likelihood of CAD and the information provided by each test.

SOURCES OF DATA

This article describes myocardial perfusion scintigraphy (MPS) and summarizes evidence for its role in stable CAD and acute coronary syndromes with particular reference to current guidelines.

AREAS OF AGREEMENT

MPS has been extensively validated for the cost-effective diagnosis and prognosis of functionally significant CAD in both the acute and chronic settings. Its use is emphasized in the current NICE, national and international guidelines.

AREAS OF CONTROVERSY

Although normal MPS is associated with good outcomes, assessments of subclinical atherosclerosis such as coronary artery calcium scoring and computed tomography coronary angiography (CTA) demonstrate that non-flow-limiting CAD remains prognostically important.

GROWING POINTS

Technological developments, such as attenuation correction to improve diagnostic accuracy or analysis of left ventricular phase to detect dyssynchrony, carry the possibility of increasing the information that can be usefully gained from a single MPS study.

AREAS TIMELY FOR DEVELOPING RESEARCH

Of particular importance will be the role of MPS in an integrated imaging strategy that involves both anatomical and functional cardiac assessments. The use of hybrid technology that combines techniques such as MPS and CTA into a single imaging unit requires careful consideration with regard to diagnostic usefulness and cost-effectiveness.

Cost-effective applications of cardiac computed tomography in coronary artery disease

Computed tomography has been introduced as a noninvasive imaging modality used for coronary artery calcium scoring in asymptomatic individuals and contrast-enhanced coronary angiography in symptomatic individuals. As the rising costs of healthcare reflect, in part, the development of these types of new expensive technologies for cardiac diagnosis, the economic considerations that surround them should be of interest to clinicians and payers alike. In this review, we discuss basic principles underlying economic efficiency analyses of medical products, using computed tomography in coronary artery disease as a case in point.

[Multidetector computed tomography coronarography: preliminary experience in real life settings]

Multidetector computed tomography coronarography (MDCT) is a promising tool, offering non invasive anatomic evaluation of coronary arteries. We relate in this article our impressions after our first two years experience.

METHODS

Retrospective study of the 328 patients who underwent MDCT examination between January 2005 and December 2006 at our community hospital. Per patient comparative analysis of the anatomical findings versus percutaneous angiography (PCA) in 61 cases.

RESULTS

Out of 328 patients 61 (18.5%) underwent PCA. In these patients we found a sensibility, specificity, positive predictive value and negative predictive value of 100%, 54%, 59% and 100% for MDCT. The main factor responsible for inconclusive vessel analysis was excessive calcification.

CONCLUSION

In routine use, MDCT enables one to rule out significant stenosis non invasively, with high sensitivity in an unselected patient population.

Prognostic Value of Dipyridamole Stress Cardiovascular Magnetic Resonance Imaging in Patients With Known or Suspected Coronary Artery Disease

OBJECTIVES

We evaluated the prognostic value of dipyridamole stress cardiovascular magnetic resonance imaging (CMR) in patients with chest pain and known or suspected coronary artery disease.

BACKGROUND

Stress perfusion CMR has been incorporated in daily practice. Data on its prognostic value are preliminary.

METHODS

Dipyridamole stress CMR was performed in 420 patients with chest pain and known or suspected coronary artery disease. The extent (number of segments according to the 17-segment model) of abnormal wall motion at rest (AWM-rest), abnormal wall motion with dipyridamole (AWM-D), perfusion deficit (at stress first-pass perfusion imaging), and delayed enhancement (at late enhancement imaging) were analyzed.

RESULTS

During a median follow-up of 420 days, 41 major adverse cardiac events (MACE), including 9 cardiac deaths, 14 nonfatal myocardial infarctions, and 18 readmissions for unstable angina with documented abnormal angiography, were documented. The MACE were more frequent in patients with significant (>1 segment) AWM-rest (22% vs. 5%), AWM-D (21% vs. 4%), perfusion deficit (17% vs. 5%), and delayed enhancement (20% vs. 6%; p <0.0001 in all cases). In a multivariate analysis adjusted for baseline characteristics, the extent of AWM-D was independently related to MACE (hazard ratio [HR] 1.15 [95% confidence interval (CI) 1.06 to 1.24] per segment; p = 0.0006) and to major events (cardiac death or nonfatal myocardial infarction; HR 1.15 [95% CI 1.05 to 1.26] per segment; p = 0.002).

CONCLUSIONS

Dipyridamole stress CMR is useful for predicting the outcome of patients with known or suspected coronary artery disease.

Myocardial infarction with normal coronary arteries: a conundrum with multiple aetiologies and variable prognosis: an update

The existence of myocardial infarction despite angiographically normal coronary arteries was recognized more than 30 years ago. Since then, various series of such patients have been described, but the aetiology and pathogenesis of the condition are still a source of debate. Evidence exists for a role of coronary vasospasm, thrombosis, embolization and inflammation, per se or combined, in determining the occurrence of myocardial infarction in the presence of angiographically normal coronary arteries. Endothelial dysfunction, possibly superimposed to nonangiographically evident atherosclerosis, may be an underlying common feature predisposing to the acute event. Additionally, myocarditis may explain some of these occurrences. Myocardial infarction with normal coronary arteries is therefore likely the result of multiple pathogenetic mechanisms. Although most reports emphasize the good prognosis of this condition, in general much better than myocardial infarction with coronary artery disease, prognosis is likely variable according to the underlying mechanism. This review summarizes current knowledge on this condition and examines areas of recent progress.