Cardiovascular magnetic resonance: contribution to the exploration of cardiomyopathies

Magnetic resonance imaging is a non-invasive and non-irradiating imaging method, complementary to cardiac ultrasound in the assessment of cardiovascular disease and implicitly of cardiomyopathies. Although it is not a first intention imaging method, it is superior in the assessment of cardiac volumes, left ventricular ejection fraction, in the analysis of cardiac wall dyskinesia and myocardial tissue characteristics with and without using a contrast agent. The purpose of this paper is to review the current knowledge regarding cardiovascular magnetic resonance imaging (CMR) and its applications in cardiomyopathy analysis.

In order to create this review, relevant articles were searched and analyzed by using MeSH terms such as: "cardiac magnetic resonance imaging", "cardiomyopathy", "myocardial fibrosis". Three main international databases PubMed, Web of Science and Medscape were searched. We carried out a narrative review focused on the current indications of cardiovascular magnetic resonance imaging in cardiomyopathies, both common and raret, of ischemic and nonischemic types.

Cardiac magnetic resonance imaging has a very important role in the diagnosis, assessment and prognosis of common cardiomyopathies (the dilated, hypertrophic and inflammatory types) or other more rare ones such as (amyloidosis, arrhythmogenic right ventricular, non-compaction or Takotsubo cardiomyopathy), as it represents the gold standard for evaluating the ejection fraction, ventricular volumes and mass. CMR techniques, such as late gadolinium enhancement, T1 and T2 mapping have proven their usefulness, helping differentiate between ischemic (subendocardial enhancement) and nonischemic cardiomyopathy (varied pattern) or also establish the etiology. Another important feature of this imaging technique is that it can establish the myocardial viability, thus the chance of contractile recovery after revascularization. This feature is based on the transmural extent of LGE, left ventricle wall thickness and the assessment of the contractile reserve after administration of low dose dobutamine.

Cardiovascular magnetic resonance imaging is an indispensable tool, with proven efficiency, capable of providing the differential diagnosis between ischemic and nonischemic cardiomyopathy or establishing the etiology in the nonischemic type. In addition, these findings have a prognostic value, they may guide the patient management plan and, if necessary, can evaluate treatment response. Therefore, this technique should be part of any routine investigation of various cardiomyopathies.