Use of cardiovascular magnetic resonance for diagnosis and management in hypertrophic cardiomyopathy

Differential Diagnosis of Thick Myocardium according to Histologic Features Revealed by Multiparametric Cardiac Magnetic Resonance Imaging

Left ventricular (LV) wall thickening, or LV hypertrophy (LVH), is common and occurs in diverse conditions including hypertrophic cardiomyopathy (HCM), hypertensive heart disease, aortic valve stenosis, lysosomal storage disorders, cardiac amyloidosis, mitochondrial cardiomyopathy, sarcoidosis and athlete’s heart. Cardiac magnetic resonance (CMR) imaging provides various tissue contrasts and characteristics that reflect histological changes in the myocardium, such as cellular hypertrophy, cardiomyocyte disarray, interstitial fibrosis, extracellular accumulation of insoluble proteins, intracellular accumulation of fat, and intracellular vacuolar changes. Therefore, CMR imaging may be beneficial in establishing a differential diagnosis of LVH. Although various diseases share LV wall thickening as a common feature, the histologic changes that underscore each disease are distinct. This review focuses on CMR multiparametric myocardial analysis, which may provide clues for the differentiation of thickened myocardium based on the histologic features of HCM and its phenocopies.

Postmortem cardiac magnetic resonance in sudden cardiac death

Postmortem imaging is increasingly used in forensic practice as good complementary tool to conventional autopsy investigations. Over the last decade, postmortem cardiac magnetic resonance (PMCMR) imaging was introduced in forensic investigations of natural deaths related to cardiovascular diseases, which represent the most common causes of death in developed countries. Postmortem CMR application has yielded interesting results in ischemic myocardium injury investigations and in visualizing other pathological findings in the heart. This review presents the actual state of postmortem imaging for cardiovascular pathologies in cases of sudden cardiac death (SCD), taking into consideration both the advantages and limitations of PMCMR application.

Myocardial fibrosis imaging based on T1-mapping and extracellular volume fraction (ECV) measurement in muscular dystrophy patients: diagnostic value compared with conventional late gadolinium enhancement (LGE) imaging

AIM

Cardiac involvement with progressive myocardial fibrosis leading to dilated cardiomyopathy is a major cause of death in muscular dystrophy patients. Extracellular volume fraction (ECV) measurement based on T1-mapping pre- and post-contrast promises the detection of early 'diffuse' myocardial fibrosis that cannot be depicted by conventional contrast-imaging based on late gadolinium enhancement (LGE). With this study, we evaluated the presence of diffuse myocardial fibrosis in regions of 'normal' (LGE-negative) and 'diseased' (LGE-positive) appearing myocardium as well as its relation to the extent of left ventricular (LV) dysfunction and the occurrence of arrhythmias in Becker muscular dystrophy (BMD) patients.

METHODS AND RESULTS

Twenty-seven BMD patients (35 ± 12 years) and 17 matched male healthy controls (33 ± 8 years) underwent cardiovascular magnetic resonance (CMR) studies including ECV measurement and LGE-imaging. Ambulatory monitoring of arrhythmic events was performed by means of an external event loop recorder. Twenty BMD patients (74%) demonstrated cardiac involvement as detected by typical inferolateral presence of LGE. Twelve patients (44%) had an impaired LV ejection fraction-all being LGE-positive. Global myocardial ECV was significantly higher in the BMD group (29 ± 6%) compared with the control group (24 ± 2%, P = 0.001). Patients with cardiac involvement demonstrated higher global ECV (31 ± 6%) as well as significantly increased regional ECV not only in LGE-positive segments (34 ± 6%), but also in LGE-negative segments (28 ± 6%) compared with BMD patients without cardiac involvement and to controls, respectively (24 ± 3 and 24 ± 2%, P = 0.005). Global ECV in patients with cardiac involvement substantially correlated to LV ejection fraction (r = -0.629, P = 0.003) and to the number of LGE-positive segments (r = 0.783, P < 0.001). On univariable analysis, global ECV-but not the categorical presence of LGE per se--was significantly associated with arrhythmic events (OR: 1.97, CI: 32.22-1.21, P = 0.032).

CONCLUSION

ECV measurement by CMR is a useful tool in assessing the total extent of myocardial fibrosis as well as in depicting subtle diffuse fibrosis in areas of normal appearing myocardium on LGE-images. Thus, myocardial ECV is a potential additional quantitative tool for accurate detection of cardiac involvement and risk stratification in muscular dystrophy patients.

Cardiovascular health, part 1: preparticipation cardiovascular screening

CONTEXT

Identification of potentially fatal cardiac conditions in otherwise healthy athletes presents a major challenge to the sports medicine community. The requirements for preparticipation screening vary among countries and even from state to state within the United States. The mandated use of an electrocardiogram as a screening implement has provoked international controversy.

EVIDENCE ACQUISITION

Part 1 of this review highlights the current guidelines and controversies surrounding cardiovascular screening, with a focus on the diagnostic challenges associated with identifying athletes with inheritable cardiomyopathies. Data sources were limited to peer-reviewed publications from 1984 to the present.

RESULTS

Preparticipation screening should include at least a history and a physical examination for all athletes, whereas use of an electrocardiogram is still controversial. Diagnosis of inherited cardiomyopathies presents unique challenges, particularly in hypertrophic cardiomyopathy, where many features can mimic those found in the "athlete's heart."

CONCLUSIONS

Recognizing cardiac conditions in athletes that can predispose them to sudden cardiac death or other adverse outcomes is of vital importance, as is the appropriate exclusion of these athletes from competition. Further studies are needed to determine the most efficient and cost-effective means of screening and to increase the sensitivity and specificity of diagnostic testing for inheritable cardiovascular diseases.

Clinical utility of cardiovascular magnetic resonance in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is characterized by substantial genetic and phenotypic heterogeneity, leading to considerable diversity in clinical course including the most common cause of sudden death in young people and a determinant of heart failure symptoms in patients of any age. Traditionally, two-dimensional echocardiography has been the most reliable method for establishing a clinical diagnosis of HCM. However, cardiovascular magnetic resonance (CMR), with its high spatial resolution and tomographic imaging capability, has emerged as a technique particularly well suited to characterize the diverse phenotypic expression of this complex disease. For example, CMR is often superior to echocardiography for HCM diagnosis, by identifying areas of segmental hypertrophy (ie., anterolateral wall or apex) not reliably visualized by echocardiography (or underestimated in terms of extent). High-risk HCM patient subgroups identified with CMR include those with thin-walled scarred LV apical aneurysms (which prior to CMR imaging in HCM remained largely undetected), end-stage systolic dysfunction, and massive LV hypertrophy. CMR observations also suggest that the cardiomyopathic process in HCM is more diffuse than previously regarded, extending beyond the LV myocardium to include thickening of the right ventricular wall as well as substantial morphologic diversity with regard to papillary muscles and mitral valve. These findings have implications for management strategies in patients undergoing invasive septal reduction therapy. Among HCM family members, CMR has identified unique phenotypic markers of affected genetic status in the absence of LV hypertrophy including: myocardial crypts, elongated mitral valve leaflets and late gadolinium enhancement. The unique capability of contrast-enhanced CMR with late gadolinium enhancement to identify myocardial fibrosis has raised the expectation that this may represent a novel marker, which may enhance risk stratification. At this time, late gadolinium enhancement appears to be an important determinant of adverse LV remodeling associated with systolic dysfunction. However, the predictive significance of LGE for sudden death is incompletely resolved and ultimately future large prospective studies may provide greater insights into this issue. These observations underscore an important role for CMR in the contemporary assessment of patients with HCM, providing important information impacting diagnosis and clinical management strategies.

Cardiovascular MRI in clinical trials: expanded applications through novel surrogate endpoints

Recent advances in cardiovascular magnetic resonance (CMR) now allow the accurate and reproducible measurement of many aspects of cardiac and vascular structure and function, with prognostic data emerging for several key imaging biomarkers. These biomarkers are increasingly used in the evaluation of new drugs, devices and lifestyle modifications for the prevention and treatment of cardiovascular disease. This review outlines a conceptual framework for the application of imaging biomarkers to clinical trials, highlights several important CMR techniques which are in use in randomised studies, and reviews certain aspects of trial design, conduct and interpretation in relation to the use of CMR.

Hypertrophic cardiomyopathy: assessment with MR imaging and multidetector CT

Hypertrophic cardiomyopathy (HCM) is a genetic cardiac disease. Its early detection is important because it is the most common cause of sudden cardiac death among young people. However, HCM is often a dilemma for clinicians because it manifests with diverse phenotypic expressions and clinical courses. With the advances in imaging technology, magnetic resonance (MR) imaging and multidetector computed tomography (CT) serve as suitable modalities for detecting and characterizing HCM and obtaining information for appropriate management of cases of HCM, although echocardiography is currently the most widely used modality. This article is an overview of the definition of HCM, its various phenotypes, risk stratification of HCM, and the potential application of cardiac MR imaging and multidetector CT for the assessment of HCM.

Acute hemodynamic changes in percutaneous transluminal septal coil embolization for hypertrophic obstructive cardiomyopathy

BACKGROUND

A 48-year-old man with hypertrophic obstructive cardiomyopathy (HOCM) presented with palpitations, symptoms of medically refractory class II angina, and NYHA class II-III heart failure.

INVESTIGATIONS

Physical examination revealed a grade 3 systolic murmur that increased to grade 4 with exercise. Echocardiography showed marked septal thickening (17 mm), a left ventricular outflow tract gradient (LVOTG) of 95 mmHg, and a 3+ systolic anterior motion of the mitral valve apparatus. No other pathology was noted with cardiac MRI or with coronary angiography.

DIAGNOSIS

Severe symptomatic HOCM.

MANAGEMENT

Coil embolization of the first two septal vessels resulted in a limited septal infarct (creatine kinase-MB 36.6 microg/l; troponin T 0.43 microg/l) that corresponded to a mass of 8.1 g on gadolinium contrast cardiac MRI. The LVOTG decreased immediately from 78 mmHg to 35 mmHg. On pressure-volume loops, contractile isovolemic and systolic ejectional parameters decreased, while an improvement in diastolic left ventricular function was observed.

CONCLUSION

Septal coil embolization acutely and effectively reduced the LVOTG in a patient with drug-refractory HOCM.

Advances in clinical applications of cardiovascular magnetic resonance imaging

Cardiovascular magnetic resonance (CMR) is an evolving technology with growing indications within the clinical cardiology setting. This review article summarises the current clinical applications of CMR. The focus is on the use of CMR in the diagnosis of coronary artery disease with summaries of validation literature in CMR viability, myocardial perfusion, and dobutamine CMR. Practical uses of CMR in non-coronary diseases are also discussed.