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.     

Application of cardiac magnetic resonance imaging in cardiomyopathy

Cardiomyopathies account for a significant portion of morbidity and mortality in patients with heart disease. The diagnosis and identification of the underlying disorder are essential for directing appropriate life-saving therapy. Cardiac magnetic resonance imaging (CMR) is an ideal method for the noninvasive evaluation of cardiomyopathies of unknown etiology. In addition, there is increasing prognostic evidence to support the use of this technology in patient risk stratification. CMR is not limited by anatomic barriers and is able to characterize tissue abnormalities that previously could often be identified only through biopsy. This review discusses the utility of CMR in the assessment of cardiomyopathies, including specific imaging techniques and their application in ischemic and nonischemic settings.     

Impact of cardiac magnetic resonance imaging in nonischemic cardiomyopathies

Non-ischemic cardiomyopathies include a wide spectrum of disease states afflicting the heart, whether a primary process or secondary to a systemic condition. Cardiac magnetic resonance imaging(CMR) has established itself as an important imaging modality in the evaluation of non-ischemic cardiomyopathies. CMR is useful in the diagnosis of cardiomyopathy, quantification of ventricular function, establishing etiology, determining prognosis and risk stratification. Technical advances and extensive research over the last decade have resulted in the accumulation of a tremendous amount of data with regards to the utility of CMR in these cardiomyopathies. In this article, we review CMR findings of various non-ischemic cardiomyopathies and focus on current literature investigating the clinical impact of CMR on risk stratification, treatment, and prognosis.     

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 Role of Cardiac MR in New-Onset Heart Failure

In patients with heart failure, cardiovascular magnetic resonance imaging (CMR) allows a multifaceted approach to cardiac evaluation by enabling an assessment of morphology, function, perfusion, viability, tissue characterization, and blood flow during a single comprehensive examination. Given its accuracy and reproducibility, many believe CMR is the reference standard for the noninvasive assessment of ventricular volumes, mass, and function, and offers an ideal means for the serial assessment of disease progression or treatment response in individual patients. Delayed-enhancement (DE)-CMR provides a direct assessment of myopathic processes. This permits a fundamentally different approach than that traditionally taken to ascertaining the etiology of cardiomyopathy, which is vital in patients with nonischemic cardiomyopathy and incidental coronary artery disease and patients with mixed, ischemic and nonischemic cardiomyopathy. Precise tissue characterization with DE-CMR also improves the diagnosis of left ventricular thrombus, for which it is the emerging clinical reference standard. There is a growing body of literature on the utility of CMR for patient risk stratification, and its potential role in important management decisions such as for cardiac resynchronization therapy and defibrillator placement.     

Reversible cardiomyopathies

Cardiomyopathy represents a diverse and heterogenous group of disorders affecting the myocardium and ultimately resulting in cardiac dysfunction. The prevalence of heart failure is high (5 million symptomatic patients in the United States) and increasing. Cardiomyopathy is the leading cause of hospitalization in patients older than 65 years of age, resulting in enormous healthcare expenditure and lost productivity. Ischemic cardiomyopathy accounts for about half of these patients, but in several large clinical trials the prevalence of potentially reversible nonischemic cardiomyopathy is also significant, ranging from 20% to 50%. There is epidemiological evidence that the prognosis of these reversible nonischemic cardiomyopathies is better than ischemic or other nonreversible cardiomyopathies. Early and precise diagnosis of the etiology of heart failure is important for determining prognosis and effective treatments.     

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.

     

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.     

Sudden death related cardiomyopathies – Arrhythmogenic right ventricular cardiomyopathy,arrhythmogenic cardiomyopathy,and exercise-induced cardiomyopathy

Sudden cardiac death (SCD) is a devastating possible outcome of all cardiomyopathies. The risk of SCD is increased in patients with structural heart disease and continues to increase as ventricular dysfunction worsens. There is, however, a subset of cardiomyopathy, so-called “arrhythmogenic cardiomyopathy” (ACM), that carries an inherent propensity for arrhythmia in all stages of the disease, even preceding ventricular dysfunction. The aim of this review is to identify cardiomyopathies, other than ischemic and dilated cardiomyopathies, that are associated with ventricular arrhythmias (VAs) and SCD. We discuss prevalence, diagnosis, natural history and management of arrhythmogenic right ventricular dysplasia/cardiomyopathy, ACM, and exercise-induced cardiomyopathy, with emphasis on the morbidity and mortality of VAs associated with these cardiomyopathies and how they can be mitigated through lifestyle modification, medical management, and implantation of cardioverter defibrillators.     

The current and emerging role of cardiovascular magnetic resonance in the diagnosis of nonischemic cardiomyopathies

Imaging plays a crucial role in the diagnosis, management, and prognosis assessment of patients with nonischemic cardiomyopathies. Over the past decade, the role of cardiovascular magnetic resonance imaging in clinical practice has been rapidly expanding. The technique's unsurpassed accuracy in defining cardiac morphology and function and ability to provide tissue characterization make it particularly well suited for the study of patients with nonischemic cardiomyopathies. In this review article, we provide an overview of the main cardiovascular magnetic resonance features of nonischemic cardiomyopathies, highlighting the diagnostic and prognostic utility of the technique in this heterogenous group of diseases.     

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.     

Sudden death in nondilated cardiomyopathies: Pathophysiology and prevention

Sudden cardiac death is a frequent cause of death and has been well studied in the setting of both ischemic and dilated cardiomyopathies. The primary and secondary prevention of sudden cardiac death has not been the focus of randomized clinical trials in the large cohort of patients with nondilated, nonischemic cardiomyopathies, however. Those disorders include hypertrophic cardiomyopathy and its apical variant, arrhythmogenic right ventricular cardiomyopathy, takotsubo cardiomyopathy, left ventricular noncompaction, cardiac amyloidosis, and cardiac sarcoidosis. In these conditions, risk stratification for sudden death is based on observational data.     

Systematic review of pregnancy in women with inherited cardiomyopathies

Pregnancy exposes women with inherited cardiomyopathies to increased risk for heart failure and arrhythmias. In this paper, we review the clinical course and management of pregnant women with the following inherited cardiomyopathies: hypertrophic cardiomyopathy, dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, left ventricular non-compaction cardiomyopathy, and restrictive cardiomyopathy. We also discuss peripartum cardiomyopathy. Pregnancy is generally well tolerated in asymptomatic patients with inherited cardiomyopathies. However, worsening of the clinical condition can occur during pregnancy, despite intensive medical treatment. If prior cardiac events, poor functional class (New York Heart Association class III or IV), or advanced left ventricular systolic dysfunction are present, the risk of maternal cardiac complications during pregnancy are markedly increased. The postpartum condition is generally no worse than the antepartum condition, but no long-term follow-up studies have been reported. Preconception evaluation and counselling are important aspects of managing women with inherited cardiomyopathies. Genetic counselling and DNA testing should be offered to all women following the diagnosis of an inherited cardiomyopathy.     

Do clinical diagnoses correlate with pathological diagnoses in cardiac transplant patients? The importance of endomyocardial biopsy

BACKGROUND:

Heart transplantation remains the last treatment option for patients with end-stage cardiac disease. Such diseases include ischemic cardiomyopathy, nonischemic cardiomyopathy and other conditions such as arrhythmogenic right ventricular dysplasia, cardiac sarcoidosis and cardiac amyloidosis.

OBJECTIVE:

To review the changes that have occurred over time in the etiology of heart disease in patients requiring heart transplantation, and to compare the clinical and histological diagnoses of explanted hearts from patients with progressive cardiac disease.

METHODS:

The pathological findings of 296 surgically excised hearts over a 20-year period (January 1987 to July 2006) at one institution were examined. Patients were separated into groups based on year of heart transplantation. The tissue was examined to determine the underlying cardiac pathology leading to congestive heart failure. Patient records were reviewed for preoperative clinical diagnoses and other relevant data, including pretransplant endomyocardial biopsy (EMB) results, information regarding left ventricular assist devices and, finally, evidence of disease recurrence in the grafted heart.

RESULTS:

A shift in the underlying etiology was found in patients who underwent heart transplantation from 1992 to 1996, and 1997 to 2001. Between 1987 and 1997, the majority of transplant cases consisted of ischemic cardiomyopathies. From 1997 to 2001, the majority of patients had nonischemic cardiomyopathies, and this trend continued to 2006. A majority of patients with ischemic and hypertrophic cardiomyopathy were diagnosed correctly (96.5% and 82%, respectively) before transplantation. Most patients diagnosed post-transplant with lymphocytic (viral, 15%), hypersensitive/eosinophilic (25%) and giant cell (100%) myocarditis, arrhythmogenic right ventricle dysplasia (100%), cardiac sarcoidosis (83%) and iron overload toxicity-associated cardiomyopathy (100%) had been misdiagnosed in pre-transplantation investigations. Investigations before transplantation did not include an EMB. Of all 296 patients, 51 patients (17%) were misdiagnosed. Excluding the patients with ischemic cardiomyopathy, 46 of 152 patients (30%) were misdiagnosed before transplantation.

CONCLUSIONS:

Although cardiac transplantation is a viable treatment option for patients with a variety of cardiac diseases, accurate diagnosis of patients before transplantation remains a priority. Accurate diagnosis of particular diseases (sarcoidosis, myocarditis, iron toxicity-associated cardiomyopathy and others) allows for proper treatment before transplantation, which may slow down disease progression and improve patient outcomes. Furthermore, it is important to accurately diagnose patients with diseases such as sarcoidosis, amyloidosis and particular types of myocarditis because these can readily recur in the grafted heart. The risk for recurrence must be known to practitioners and, most importantly, to the patient. We strongly recommend the use of EMB if a nonischemic cardiomyopathy is suspected, because the results may alter the diagnosis and modify the treatment strategy.     

Walking with Gianluca Di Bella during the development of clinical cardiac imaging

Cardiac magnetic resonance imaging (MRI) for the diagnosis and management of many cardiac diseases has been established in clinical practice. It provides anatomic and functional information and is the most precise technique for quantification of ventricular volume, function and mass. Among cardiac MRI sequences used in clinical practice, delayed contrast enhancement is an accurate and reliable method used in the diagnosis of ischemic and nonischemic cardiomyopathies. In addition, new technology applied in echocardiographic imaging has permitted quantification of myocardial deformations with 2-dimensional strain imaging (longitudinal, circumferential and radial strain). Cardiac MRI and echocardiography therefore both play a crucial role in the diagnosis and management of cardiovascular disease. Dr. Di Bella and colleagues have defined the roles of cardiac MRI and echocardiography in many clinical and experimental settings.     

Usefulness of electron beam computed tomography scanning for distinguishing ischemic from nonischemic cardiomyopathy

Objectives. This study was undertaken to evaluate the ability of electron beam computed tomography (EBCT) to distinguish ischemic from nonischemic causes of cardiomyopathy by evaluating heart failure patients for coronary calcification (CC).Background. The etiology of heart failure, whether coronary-induced or nonischemic, may be difficult to discern clinically. Differentiation of ischemic from nonischemic etiology is clinically important for both therapeutic and prognostic implications. With its ability to noninvasively discern and quantitate coronary artery calcification, EBCT correlates well with angiographic stenosis and thus may be useful in distinguishing ischemic and nonischemic cardiomyopathies.Methods. One hundred and twenty-five patients with cardiomyopathy (ejection fraction <0.40) and known coronary anatomy underwent EBCT coronary scanning to evaluate for CCs within 3 months of coronary angiography.Results. Of the 72 patients who were found to have ischemic cardiomyopathy, 71 patients had CC by EBCT (sensitivity 99%, p < 0.001), mean score 798 ± 899. In comparison, among the 53 patients without significant coronary artery disease (CAD) (nonischemic cardiomyopathy), the mean score was significantly lower (17 ± 51; p < 0.0001), and 44 patients had a CC score of 0 (no CC present). The specificity of EBCT to exclude CAD in patients with cardiomyopathy was 83%, using a threshold CC score of 0, and 92% for scores <80 (p < 0.001). Overall accuracy for determining the etiology of cardiomyopathy (differentiating ischemic from nonischemic) was 92% for this technique.Conclusions. This prospective, blinded study indicates that EBCT detected CC accurately and can noninvasively distinguish between cardiomyopathy because of CAD and nonischemic causes of left ventricular dysfunction.     

Assessment of myocardial fibrosis with cardiovascular magnetic resonance

Diffuse interstitial or replacement myocardial fibrosis is a common feature of a broad variety of cardiomyopathies. Myocardial fibrosis leads to impaired cardiac diastolic and systolic function and is related to adverse cardiovascular events. Cardiovascular magnetic resonance (CMR) may uniquely characterize the extent of replacement fibrosis and may have prognostic value in various cardiomyopathies. Myocardial longitudinal relaxation time mapping is an emerging technique that could improve CMR's diagnostic accuracy, especially for interstitial diffuse myocardial fibrosis. As such, CMR could be integrated in the monitoring and therapeutic management of a large number of patients. This review summarizes the advantages and limitations of CMR for the assessment of myocardial fibrosis.     

Feature-Tracking Global Longitudinal Strain Predicts Death in a Multicenter Population of Patients With Ischemic and Nonischemic Dilated Cardiomyopathy Incremental to Ejection Fraction and Late Gadolinium Enhancement

Objectives

The aim of this study was to evaluate the prognostic value of cardiac magnetic resonance (CMR) feature-tracking–derived global longitudinal strain (GLS) in a large multicenter population of patients with ischemic and nonischemic dilated cardiomyopathy.

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.     

Role of left ventricular twist mechanics in cardiomyopathies,dance of the helices

Left ventricular twist is an essential part of left ventricular function. Nevertheless, knowledge is limited in “the cardiology community” as it comes to twist mechanics. Fortunately the development of speckle tracking echocardiography, allowing accurate, reproducible and rapid bedside assessment of left ventricular twist, has boosted the interest in this important mechanical aspect of left ventricular deformation. Although the fundamental physiological role of left ventricular twist is undisputable, the clinical relevance of assessment of left ventricular twist in cardiomyopathies still needs to be established. The fact remains; analysis of left ventricular twist mechanics has already provided substantial pathophysiological understanding on a comprehensive variety of cardiomyopathies. It has become clear that increased left ventricular twist in for example hypertrophic cardiomyopathy may be an early sign of subendocardial (microvascular) dysfunction. Furthermore, decreased left ventricular twist may be caused by left ventricular dilatation or an extensive myocardial scar. Finally, the detection of left ventricular rigid body rotation in noncompaction cardiomyopathy may provide an indispensible method to objectively confirm this difficult diagnosis. All this endorses the value of left ventricular twist in the field of cardiomyopathies and may further encourage the implementation of left ventricular twist parameters in the “diagnostic toolbox” for cardiomyopathies.