Diagnostic Accuracy of Magnetocardiography in Inflammatory Cardiomyopathies: A Comparison With Noninvasive Cardiovascular Magnetic Resonance (CMR) and Invasive Endomyocardial Biopsy

Inflammatory cardiomyopathy is one of the most common causes of sudden cardiac death in young adults, as it frequently remains undetected. Also, it is a common cause of heart failure, which may lead to circulatory collapse, requiring mechanical circulatory support or heart transplant. Some patients may require immunosuppression in addition to standard heart failure therapy. Early initiation of therapy is crucial for optimal outcomes.

Inflammatory disease of the heart muscle/inflammatory cardiomyopathy can be challenging to diagnose because it often requires expensive, time intense, and sometimes invasive testing, such as cardiac magnetic resonance imaging (MRI) and endomyocardial biopsies (EMB). As a result, there is an unmet clinical need for low threshold diagnostic screening in patients with suspected cardiomyopathy.

In this study the investigator's evaluate the diagnostic accuracy of magnetocardiography (MCG) in detecting inflammatory and other types of cardiomyopathy. Diagnostic accuracy will be compared to results from advanced imaging (cardiac magnetic resonance (CMR) imaging and/or positron emission computed tomography (PET-CT)) and where available to histology from endomyocardial biopsy/EMB.

CMR provides comprehensive structural and functional data while detecting consequences of inflammation, such as edema and late gadolinium enhancement. PET-CT detects the level of activity and the extent of inflammation through measurement of glucose metabolism. However, it cannot be applied frequently because of the associated radiation exposure. EMB is the gold standard for definitive diagnosis of inflammatory cardiomyopathy and is crucial for initiation of immunosuppressive therapy, as active viral infection should be excluded. However, the limited diagnostic yield due to sampling error and risk of potential complications limit its use to selected cases where there is a high suspicion that specific treatment may be necessary.

MCG is based on detecting the movement of ions in the myocardium. When an action potential in the heart is generated, it creates voltage changes and consequently an electromagnetic field. The strength and direction of this field are affected by the flow of ions both inside and outside the cells. Typically, the magnetic field produced by the heart ranges from from 10-15 to 11-11 Tesla.