Role of Cardiac Magnetic Resonance in Non Ischemic Cardiomyopathy

Nonischemic cardiomyopathy is considered as a variety of structural and functional myocardial disorders in which the myocardium is abnormal in the absence of diseases such as hypertension and coronary artery, valvular, and congenital heart diseases. Classification of cardiomyopathies is complex, with many available systems. The American Heart Association broadly divides them into primary and secondary types. The European Society of Cardiology classifies cardiomyopathies into several distinct morphologic and functional phenotypes, each of which can be further subclassified into familial and nonfamilial forms . There is an overlap between genetic and acquired cardiomyopathies, especially in the category of dilated cardiomyopathies.

Cardiomyopathy has a prevalence of 0.02% of the population with annual death rates up to 25,000 in the United States. Nonischemic cardiomyopathy is more common in younger individuals and women.

Although echocardiography is the simplest imaging technique used for screening, diagnosis and classification of cardiomyopathies on the basis of morphology, it is operator dependent , has no tissue characterization capabilities and limited field of view especially in obese/chronic obstructive pulmonary disease patients, influenced by acoustic window, is not adequate in the evaluation of the right ventricle or extra-cardiac associated chest manifestations where magnetic resonance is superior in this issue . Transesophageal echocardiography has a better acoustic window, but it is an invasive procedure.

In comparison, cardiac multidetector computed tomography is less useful for the assessment of such cases currently because multidetector computed tomography involves radiation exposure and contrast medium- related problems and provides less information (ie, hemodynamic information, tissue characterization such as fibrosis) than magnetic resonance imaging does. Computed tomography would be more appropriate in specific requests to detect coronary calcification, exclude coronary artery disease and in those cases with contraindications for magnetic resonance imaging, such as a pacemaker.

Cardiac magnetic resonance imaging has been established as the best three dimensional imaging modality with the ability to assess cardiac morphology, ventricular function, perfusion, viability and imaging characteristics of the surrounding vasculature without ionizing radiation. The accurate treatment of patients with cardiac disorders has created the need for accurate and reproducible measurements of cardiac chamber volumes and function. Cardiac magnetic resonance has the ability to provide this information as well as assess oedema, perfusion, viability and vascular anatomy.