Application of Magnetocardiography to Screen for Inflammatory Cardiomyopathy and Monitor Treatment Response

Abstract

Background Inflammatory cardiomyopathy is one of the most common causes of sudden cardiac death in young adults. Diagnosis of inflammatory cardiomyopathy remains challenging, and better monitoring tools are needed. We present magnetocardiography as a method to diagnose myocardial inflammation and monitor treatment response. Methods and Results A total of 233 patients were enrolled, with a mean age of 45 (±18) years, and 105 (45%) were women. The primary analysis included 209 adult subjects, of whom 66 (32%) were diagnosed with inflammatory cardiomyopathy, 17 (8%) were diagnosed with cardiac amyloidosis, and 35 (17%) were diagnosed with other types of nonischemic cardiomyopathy; 91 (44%) did not have cardiomyopathy. The second analysis included 13 patients with inflammatory cardiomyopathy who underwent immunosuppressive therapy after baseline magnetocardiography measurement. Finally, diagnostic accuracy of magnetocardiography was tested in 3 independent cohorts (total n=23) and 1 patient, who developed vaccine‐related myocarditis. First, we identified a magnetocardiography vector to differentiate between patients with cardiomyopathy versus patients without cardiomyopathy (vector of ≥0.051; sensitivity, 0.59; specificity, 0.95; positive predictive value, 93%; and negative predictive value, 64%). All patients with inflammatory cardiomyopathy, including a patient with mRNA vaccine‐related myocarditis, had a magnetocardiography vector ≥0.051. Second, we evaluated the ability of the magnetocardiography vector to reflect treatment response. We observed a decrease of the pathologic magnetocardiography vector toward normal in all 13 patients who were clinically improving under immunosuppressive therapy. Magnetocardiography detected treatment response as early as day 7, whereas echocardiographic detection of treatment response occurred after 1 month. The magnetocardiography vector decreased from 0.10 at baseline to 0.07 within 7 days ( P =0.010) and to 0.03 within 30 days ( P <0.001). After 30 days, left ventricular ejection fraction improved from 42.2% at baseline to 53.8% ( P <0.001). Conclusions Magnetocardiography has the potential to be used for diagnostic screening and to monitor early treatment response. The method is valuable in inflammatory cardiomyopathy, where there is a major unmet need for early diagnosis and monitoring response to immunosuppressive therapy.

Case report: Recurrence of inflammatory cardiomyopathy detected by magnetocardiography

“…The patient underwent MCG measurement as part of his follow-up examination (Figures 3, 4). MCG supported the recurrence of inflammatory cardiomyopathy by detecting a pathological Tbeg-Tmax vector with a value of 0.069 (reference Tbeg-Tmax <0.051, Figure 4) (9). Fluorodeoxyglucose positron emission tomography-computed tomography (FDG-PET-CT) was used to screen for recurrent inflammation.…”

“…FIGURE 3 Magnetocardiography (MCG) vector during long-term immunosuppressive treatment throughout the second episode of inflammatory cardiomyopathy. In the time between April and August 2021, the vector normalized (<0.051 is considered normal)(9).…”

COVID-19, Myocarditis and Pericarditis

“… 31 , 77 There has been some controversy regarding the effect of immunosuppressive therapies such as glucocorticoids for myocarditis, while recent long-term data support its benefits. 78 , 79 Successful application of anti-inflammatory approaches in patients with COVID-19 has been reported in the literature, likely because of the overwhelming proinflammatory and cytokine response observed early after SARS-CoV-2 infection. 31 , 80 , 81…”

Vector magnetocardiography using compact optically-pumped magnetometers

“…This characteristic can enhance the precision of cardiac source localization and facilitates the establishment of comprehensive cardiac models [ 13 , 14 ]. The utilization of MCG as a diagnostic technique holds promising advantages for the early detection of myocardial ischemia and other indicative symptoms of heart disease [ 15 ]. In most instances, MCG measurements solely record the magnetic field component that is perpendicular to the chest surface [ 3 ].…”

“…For example, in patients with myocarditis receiving immunosuppressive treatment, vector SQUID-MCG can detect changes in myocardial inflammation as early as the seventh day of treatment, while echocardiography requires 30 days of treatment to observe corresponding improvement. Therefore, it can provide clinicians with earlier and more accurate diagnostic evidence, which is helpful for early intervention and treatment of myocardial inflammation [ 15 ]. In the application of fetal MCG (fMCG), to avoid the signal influence affected by fetal orientation and movement, vector MCG is potentially useful for standardization of the fMCG waveforms and to provide a more complete and accurate analysis of fetal arrhythmias [ 16 ].…”