Cardiac magnetic resonance imaging for stage B heart failure

Cardiac magnetic resonance imaging (CMR) can play a key role in the assessment and follow-up of patients with stage B heart failure. CMR currently serves as the reference standard for quantifying right and left ventricular size and ejection fraction. Technical advances have also enabled CMR to provide noninvasive tissue characterization and detailed assessments of myocardial performance. Thus, in addition to standard metrics of cardiac structure and function, CMR offers a variety of tools for determining cause, severity, and estimating the prognosis associated with an asymptomatic cardiomyopathy.     

Assessment of ventricular structure and function with multidetector CT and MRI

Accurate, noninvasive assessment of ventricular function is fundamental to providing excellent care to patients with cardiovascular diseases. Three-dimensional imaging using cardiac magnetic resonance (CMR) permits the measurement of ventricular structure and function with such precision and accuracy that it now serves as the standard of reference for this purpose. Multidetector CT (MDCT) permits similar three-dimensional reconstruction and measurement of ventricular function. Available data indicate there is good agreement between MDCT and CMR measurements of ventricular function. Patients with cardiomyopathy and distorted ventricles stand to benefit the most from these techniques, particularly with the possibility of combined noninvasive angiography and systolic function assessment with MDCT.     

Assessment of myocardial viability: comparison of echocardiography versus cardiac magnetic resonance imaging in the current era

Detecting viable myocardium, whether hibernating or stunned, is of clinical significance in patients with coronary artery disease and left ventricular dysfunction. Echocardiographic assessments of myocardial thickening and endocardial excursion during dobutamine infusion provide a highly specific marker for myocardial viability, but with relatively less sensitivity. The additional modalities of myocardial contrast echocardiography and tissue Doppler have recently been proposed to provide further, quantitative measures of myocardial viability assessment. Cardiac magnetic resonance (CMR) has become popular for the assessment of myocardial viability as it can assess cardiac function, volumes, myocardial scar, and perfusion with high-spatial resolution. Both 'delayed enhancement' CMR and dobutamine stress CMR have important roles in the assessment of patients with ischaemic cardiomyopathy. This article reviews the recent advances in both echocardiography and CMR for the clinical assessment of myocardial viability. It attempts to provide a pragmatic approach toward the patient-specific assessment of this important clinical problem.     

The emerging role of MRI in the diagnosis and management of cardiomyopathies

Cardiac magnetic resonance (CMR) has emerged as an important tool for the evaluation of cardiomyopathies, providing highly accurate information on the macroscopic changes of cardiac morphology, function, and tissue composition. For myocardial tissue characterization, the technique of myocardial delayed enhancement is a potentially promising tool for diagnosis, management, and prognosis. Several CMR approaches are now available to better diagnose and prognosticate dilated cardiomyopathy, hypertrophic cardiomyopathy, restrictive cardiomyopathy, arrhythmogenic right ventricular disease, myocarditis, and other cardiomyopathies.     

Role of cardiac MRI in nonischemic cardiomyopathies

Cardiac magnetic resonance (CMR) with its higher spatial resolution is considered the gold standard for evaluating ventricular mass, volumes, and ejection fraction. CMR can be used for accurate diagnosis of several conditions, especially cardiomyopathies. The purpose of this article is to review the utility of CMR in the diagnosis and management of nonischemic cardiomyopathies. We have reviewed both common and rare types of nonischemic cardiomyopathies in detail and elaborated on the specific CMR findings in each. We believe that CMR is an invaluable tool, not only in differentiating nonischemic from ischemic cardiomyopathy, but also in aiding the accurate diagnosis and management of the subtype of nonischemic cardiomyopathy. CMR should routinely be integrated in the diagnostic workup of various cardiomyopathies.     

The role of cardiovascular magnetic resonance imaging in the diagnosis and prognosis of patients with heart failure

Cardiovascular magnetic resonance (CMR) imaging is a tomographic technique, which allows three-dimensional slice orientation without limitations from acoustic windows inherent to echocardiography. Further advantages of CMR are its high temporal and spatial resolution, its excellent soft tissue resolution and its high blood-to-tissue contrast. Cardiovascular magnetic resonance is currently the only imaging technique, which provides a comprehensive study of both structure and function of the heart as well as myocardial perfusion and viability. Moreover, post-processing of CMR images does not require any geometric assumptions as in echocardiography to determine ventricular dimensions. This is particularly important when evaluating ventricles of patients with chronic heart failure with severely altered morphology that may have regional variations in wall thickness and contractility at least in ischemic cardiomyopathy. The highly reproducible results of CMR imaging have turned this technique into a reference standard for the non-invasive assessment of ventricular dimensions, mass and function. In cases with indeterminate results of clinical, electrocardiographic and particularly echocardiographic findings CMR should be used early in the process of diagnosis of patients with heart failure. Not only can altered structure and degree of ventricular and valvular dysfunctions be accurately assessed but also regional perfusion deficits and/or myocardial scars are easily detected. For therapeutic and prognostic reasons a simple differentiation between ischemic and non-ischemic cardiomyopathy should be achieved as the first diagnostic step. In addition, the type and localization of the late gadolinium enhancement (LGE) phenomenon may aid in non-invasively differentiating the etiology of non-ischemic cardiomyopathy. CMR may also improve the assessment and extent of interventricular and intraventricular dyssynchrony in patients to be selected for cardiac resynchronization therapy (CRT). Lastly, the LGE phenomenon may provide independent prognostic information in patients with a CRT system implanted, as well as in patients with ischemic and non-ischemic cardiomyopathy. Thus, CMR imaging should be implemented early in the diagnostic process of patients with heart failure to significantly improve the speed and accuracy of diagnostic procedures, to control the effect of therapeutic measures, and to select patients with a limited prognosis by assessing the degree of ventricular dysfunction and the extent of myocardial scarring.     

Distribution of late gadolinium enhancement in various types of cardiomyopathies:Significance in differential diagnosis,clinical features and prognosis

The recent development of cardiac magnetic resonance(CMR)techniques has allowed detailed analyses of cardiac function and tissue characterization with high spatial resolution.We review characteristic CMR features in ischemic and non-ischemic cardiomyopathies(ICM and NICM),especially in terms of the location and distribution of late gadolinium enhancement(LGE).CMR in ICM shows segmental wall motion abnormalities or wall thinning in a particular coronary arterial territory,and the subendocardial or transmural LGE.LGE in NICM generally does not correspond to any particular coronary artery distribution and is located mostly in the mid-wall to subepicardial layer.The analysis of LGE distribution is valuable to differentiate NICM with diffusely impaired systolic function,including dilated cardiomyopathy,end-stage hypertrophic cardiomyopathy(HCM),cardiac sarcoidosis,and myocarditis,and those with diffuse left ventricular(LV)hypertrophy including HCM,cardiac amyloidosis and Anderson-Fabry disease.A transient low signal intensity LGE in regions of severe LV dysfunction is a particular feature of stress cardiomyopathy.In arrhythmogenic right ventricular cardiomyopathy/dysplasia,an enhancement of right ventricular(RV)wall with functional and morphological changes of RV becomes apparent.Finally,the analyses of LGE distribution have potentials to predict cardiac outcomes and response to treatments.     

Sudden Cardiac Death Risk Prediction: The Role of Cardiac Magnetic Resonance Imaging

Sudden cardiac death (SCD) accounts for more than 4 million global deaths per year. While it is most commonly caused by coronary artery disease, a final common pathway of ventricular arrhythmias is shared by different etiologies. The most effective primary and secondary prevention strategy is an implantable cardioverter-defibrillator (ICD). The decision to implant an ICD for primary prevention is largely based on a left ventricular ejection fraction ≤ 35%, but this criterion in isolation is neither sensitive nor specific. Novel imaging parameters hold promise to improve ICD candidate selection. Cardiac magnetic resonance (CMR) imaging is a powerful and versatile technique, with the ability to comprehensively assess cardiac structure and function. A range of variables based on CMR techniques (late gadolinium enhancement, T₁ mapping, T₂* relaxometry, deformation imaging) have been associated with ventricular arrhythmias and SCD risk. The role of CMR in the estimation of ventricular arrhythmias and SCD risk in coronary artery disease, nonischemic cardiomyopathies, cardiac transplant, iron-overload cardiomyopathy and valvular heart disease is reviewed in this article. Prospective, randomized trials and standardization of CMR techniques are required before its routine use can be recommended for guiding SCD prevention strategies.     

The emerging clinical role of cardiovascular magnetic resonance imaging

Starting as a research method little more than a decade ago, cardiovascular magnetic resonance (CMR) imaging has rapidly evolved to become a powerful diagnostic tool used in routine clinical cardiology. The contrast in CMR images is generated from protons in different chemical environments and, therefore, enables high-resolution imaging and specific tissue characterization in vivo, without the use of potentially harmful ionizing radiation.CMR imaging is used for the assessment of regional and global ventricular function, and to answer questions regarding anatomy. State-of-the-art CMR sequences allow for a wide range of tissue characterization approaches, including the identification and quantification of nonviable, edematous, inflamed, infiltrated or hypoperfused myocardium. These tissue changes are not only used to help identify the etiology of cardiomyopathies, but also allow for a better understanding of tissue pathology in vivo. CMR tissue characterization may also be used to stage a disease process; for example, elevated T2 signal is consistent with edema and helps differentiate acute from chronic myocardial injury, and the extent of myocardial fibrosis as imaged by contrast-enhanced CMR correlates with adverse patient outcome in ischemic and nonischemic cardiomyopathies.The current role of CMR imaging in clinical cardiology is reviewed, including coronary artery disease, congenital heart disease, nonischemic cardiomyopathies and valvular disease.     

The Prognostic Role of Late Gadolinium Enhancement Magnetic Resonance Imaging in Patients With Cardiomyopathy

Cardiovascular magnetic resonance imaging (CMRI) is currently considered part of standard care at many academic centres for the evaluation of patients with ischemic or nonischemic cardiomyopathy. While CMRI provides unparalleled diagnostic versatility for the assessment of myocardial function, perfusion, and tissue health, evidence supporting its prognostic value for the prediction of important cardiovascular events is now emerging. Given the low specificity of currently available clinical markers in patients with cardiomyopathy, more-robust biomarkers aimed at identifying those at high risk of sudden cardiac death and other relevant outcomes are desirable. Late gadolinium enhancement (LGE) CMRI offers the novel capacity to quantify the burden of myocardial fibrosis, a common pathophysiological end point of most cardiomyopathy states. As such, it has the potential to be a robust and ubiquitous marker of cardiovascular events related to the presence of advanced tissue disease. This review paper focuses on the evidence to date supporting LGE imaging as a tool for the prediction of future cardiovascular events in patients with ischemic and nonischemic cardiomyopathy.     

The additional value of gadolinium-enhanced MRI to standard assessment for cardiac involvement in patients with pulmonary sarcoidosis

AIM: To determine whether gadolinium-enhanced cardiac MRI (CMR) was of additional diagnostic value to standard assessment in patients with sarcoidosis who underwent evaluation for cardiac involvement. METHODS: We reviewed the findings in patients with pulmonary sarcoidosis who had been assessed with ECG, Doppler echocardiography, 201Tl scintigraphy, and CMR from 2002 to 2004. RESULTS: Of the 55 evaluated patients, standard evaluation diagnosed cardiac involvement in 13 patients while CMR diagnosed myocardial scarring (mean +/- SD, 2.5 +/- 1.9 segments) [all 6 patients] and impaired systolic left ventricular function (1 patient) in an additional 6 patients. The extent of delayed enhancement correlated with disease duration (p < 0.05), ventricular dimensions and function (p < 0.001), severity of mitral regurgitation (p < 0.05), and the presence of ventricular tachycardias (p < 0.001). Patients in whom cardiac involvement was diagnosed only with CMR had less myocardial scarring and functional impairment (p < 0.05) compared to patients with a diagnosis made by standard assessment. CONCLUSION: CMR provides an accurate estimation of the extent of cardiac involvement and may reveal signs of early infiltration that are not detected by standard assessment. The extent of late enhancement with gadolinium relates to the severity of cardiac involvement and may therefore have prognostic implications.     

Cardiovascular magnetic resonance and the evaluation of heart failure

Cardiovascular magnetic resonance (CMR) has established itself as probably the single best way of phenotyping the failing heart. It is the accepted gold standard for measuring cardiac function, volumes, and mass, but within the same scan session additional techniques are available for greater definition. Tissue characterization with the contrast agent gadolinium is well validated and allows the precise visualization and quantification of myocardial infarction. This can be used for viability assessment and to determine heart failure etiology. Dobutamine stress CMR and CMR perfusion hold advantages over conventional techniques. The new frontiers of CMR in heart failure hold the promise of unique insights quantifying myocardial iron, nonischemic fibrosis, microvascular perfusion, plaque characterization, and CMR-targeted intervention. The development and validation of these techniques represent major research challenges for the future. From a clinical perspective, an equal challenge is in increasing the availability of the modality for patients and physicians.     

Cardiac Imaging Integration in 2009 and Beyond: Cardiovascular magnetic resonance

Cardiovascular magnetic resonance (CMR) is currently well recognized in clinical practice for the diagnosis and management of cardiovascular diseases. CMR is helpful in the diagnosis and prognosis of patients with myocardial infarction. The high spatial resolution of CMR enables accurate assessment of tissue characterization in various types of cardiomyopathy. In addition, CMR may play a complementary role with echocardiography in clinical evaluation of patients with valvular and congenital heart disease.     

Myocardial Amyloidosis: The Exemplar Interstitial Disease

Cardiac involvement drives prognosis and treatment choices in cardiac amyloidosis. Echocardiography is the first-line examination for patients presenting with heart failure, and it is the imaging modality that most often raises the suspicion of cardiac amyloidosis. Echocardiography can provide an assessment of the likelihood of cardiac amyloid infiltration versus other hypertrophic phenocopies and can assess the severity of cardiac involvement. Visualizing myocardial amyloid infiltration is challenging and, until recently, was restricted to the domain of the pathologist. Two tests are transforming this: cardiac magnetic resonance (CMR) imaging and bone scintigraphy. After the administration of contrast, CMR is highly sensitive and specific for the 2 main types of ventricular myocardial amyloidosis, light chain amyloidosis (AL) and transthyretin amyloidosis (ATTR). CMR structural and functional assessment combined with tissue characterization can redefine cardiac involvement by tracking different disease processes, ranging from amyloid infiltration, to the myocardial response associated with amyloid deposition, through the visualization and quantification of myocardial edema and myocyte response. Bone scintigraphy (paired with exclusion of serum free light chains) is emerging as the technique of choice for distinguishing ATTR from light chain cardiac amyloidosis and other cardiomyopathies; it has transformed the diagnostic pathway for ATTR, allowing noninvasive diagnosis of ATTR without the need for a tissue biopsy in the majority of patients. CMR with tissue characterization and bone scintigraphy are rewriting disease understanding, classification, and definition, and leading to a change in patient care.     

Peripartum cardiomyopathy-diagnosis,management, and long term implications

Peripartum cardiomyopathy (PPCM) is a potentially life-threatening pregnancy-associated disease that typically arises in the peripartum period. While the disease is relatively uncommon, its incidence is rising. It is a form of idiopathic dilated cardiomyopathy, defined as pregnancy-related left ventricular dysfunction, diagnosed either towards the end of pregnancy or in the months following delivery, in women without any other identifiable cause. The clinical presentation, diagnostic assessment and treatment usually mirror that of other forms of cardiomyopathy. Timing of delivery and management require a multidisciplinary approach and individualization. Subsequent pregnancies generally carry risk, but individualization is required depending on the pre-pregnancy left ventricular function. Recovery occurs in most women on standard medical therapy for heart failure with reduced ejection fraction, more frequently than in other forms of nonischemic cardiomyopathy. The purpose of this review is to summarize the current state of knowledge with regard to diagnosis, treatment and management, with a focus on long term implications.     

Assessment of myocardial ischemia and viability using cardiac magnetic resonance

In the past decade, cardiac magnetic resonance (CMR) has evolved dramatically. Its clinical applications are now a major tool in the diagnosis and prognostic assessment of patients with ischemic heart disease. CMR can be used for detection and quantification of ischemia and for viability assessment using different techniques that are now well validated. Scar can be easily detected using contrast enhancement (late gadolinium enhancement). Ischemia detection is usually achieved with stress CMR techniques, whereas prediction for the recovery of function (detection of dysfunctional but viable myocardial segments) can be deduced from scar and stress imaging. Although determination of which approach is better may depend on the population group, the major advantage of CMR is the ability to integrate different information about anatomy, wall motion, myocardial perfusion, and tissue characterization in a single comprehensive examination.     

The Role of Cardiovascular Magnetic Resonance in Sports Cardiology; Current Utility and Future Perspectives

Purpose of review

Cardiovascular magnetic resonance (CMR) is frequently used in the investigation of suspected cardiac disease in athletes. In this review, we discuss how CMR can be used in athletes with suspected cardiomyopathy with particular reference to volumetric analysis and tissue characterization. We also discuss the finding of non-ischaemic fibrosis in athletes describing its prevalence, distribution and clinical importance.

Recent findings

The strengths of CMR include high spatial resolution, unrestricted imaging planes and lack of ionizing radiation. Regular physical exercise leads to cardiac remodeling that in certain situations can be clinically challenging to differentiate from various cardiomyopathies. Thorough morphological assessment by CMR is fundamental to ensuring accurate diagnosis. Developments in tissue characterization by late gadolinium enhancement and T1 mapping have the potential to be powerful additional tools in this challenging clinical situation. Using late gadolinium enhancement, it is also possible to detect non-ischaemic fibrosis in athletes who do not have overt cardiomyopathy. The mechanisms of this fibrosis are unclear; however, it does appear to be clinically important. We also review data on the prevalence of non-ischaemic fibrosis in athletes.

Summary

CMR is a powerful tool to aid in the diagnosis of cardiomyopathy in athletes. It may also have a future role in assessing fibrosis related to long-term participation in sport.

     

Heart failure etiology affects peripheral vascular endothelial function after cardiac transplantation

OBJECTIVES: The goal of this study was to examine the effect of heart failure etiology on peripheral vascular endothelial function in cardiac transplant recipients. BACKGROUND: Peripheral vascular endothelial dysfunction occurs in patients with heart failure of either ischemic or nonischemic etiology. The effect of heart failure etiology on peripheral endothelial function after cardiac transplantation is unknown. METHODS: Using brachial artery ultrasound, endothelium-dependent, flow-mediated dilation (FMD) was assessed in patients with heart failure with either nonischemic cardiomyopathy (n = 10) or ischemic cardiomyopathy (n = 7), cardiac transplant recipients with prior nonischemic cardiomyopathy (n = 10) or prior ischemic cardiomyopathy (n = 10) and normal controls (n = 10). RESULTS: Patients with heart failure with either ischemic cardiomyopathy or nonischemic cardiomyopathy had impaired FMD (3.6 +/- 1.0% and 5.1 +/- 1.2%, respectively, p = NS) compared with normal subjects (13.9 +/- 1.3%, p < 0.01 compared with either heart failure group). In transplant recipients with antecedent nonischemic cardiomyopathy, FMD was markedly higher than that of heart failure patients with nonischemic cardiomyopathy (13.0 +/- 2.4%, p < 0.001) and similar to that of normal subjects (p = NS). However, FMD remained impaired in transplant recipients with prior ischemic cardiomyopathy (5.5 +/- 1.5%, p = 0.001 compared with normal, p = 0.002 vs. transplant recipients with previous nonischemic cardiomyopathy). CONCLUSIONS: Peripheral vascular endothelial function is normal in cardiac transplant recipients with antecedent nonischemic cardiomyopathy, but remains impaired in those with prior ischemic cardiomyopathy. In contrast, endothelial function is uniformly abnormal for patients with heart failure, regardless of etiology. These findings indicate that cardiac transplantation corrects peripheral endothelial function for patients without ischemic heart disease, but not in those with prior atherosclerotic coronary disease.     

Quantitative ultrasonic imaging: Tissue characterization and instantaneous quantification of cardiac function

Quantitative myocardial tissue characterization is being developed to complement and expand conventional echocardiography by delineating the physical state of myocardium under diverse pathophysiologic conditions. Real-time quantitative integrated backscatter imaging has already been applied to patients with ischemic heart disease, hypertrophic cardiomyopathy, and cardiac allograft rejection in clinical investigations performed in the United States, Europe, and Japan. A recently introduced modification of imaging processing algorithms employed for characterization of tissue facilitates automatic detection of endocardial-blood interfaces and on-line quantification of ventricular size and function. Further progress and anticipated developments in quantitative ultrasonic imaging will undoubtedly augment the clinical applications of tissue characterizations based on myocardial integrated backscatter for improved diagnosis, elucidation of pathophysiology, and assessment of cardiac function.