Cardiovascular magnetic resonance (CMR) in restrictive cardiomyopathies

The restrictive cardiomyopathies constitute a heterogeneous group of myocardial diseases with a different pathogenesis and overlapping clinical presentations. Diagnosing them frequently poses a challenge. Echocardiography, electrocardiograms and laboratory tests may show non-specific changes. In this context, cardiac magnetic resonance (CMR) may play a crucial role in defining the diagnosis and guiding treatments, by offering a robust myocardial characterization based on the inherent magnetic properties of abnormal tissues, thus limiting the use of endomyocardial biopsy. In this review article, we explore the role of CMR in the assessment of a wide range of myocardial diseases causing restrictive patterns, from iron overload to cardiac amyloidosis, endomyocardial fibrosis or radiation-induced heart disease. Here, we emphasize the incremental value of novel relaxometric techniques such as T1 and T2 mapping, which may recognize different storage diseases based on the intrinsic magnetic properties of the accumulating metabolites, with or without the use of gadolinium-based contrast agents. We illustrate the importance of these CMR techniques and their great support when contrast media administration is contraindicated. Finally, we describe the useful role of cardiac computed tomography for diagnosis and management of restrictive cardiomyopathies when CMR is contraindicated.