The MagMa Study: Quantum Magnetocardiography in Cardiomyopathy

Rapid diagnostic screening is an unmet need in patients with suspected cardiomyopathy (CM). The authors recently demonstrated in a retrospective study that magnetocardiography (MCG) may be a suitable tool to detect CM.

This study aims to prospectively evaluate the accuracy of MCG as a screening tool in patients with suspected CM.

MCG uses a superconducting quantum interference device to detect the magnetic field of the heart. In another recent retrospective study by the same investigators, a T-beg-Tmax (MCG score) ≥0.051 identified patients with CM (dilated, hypertrophic, nondilated left ventricular, and restrictive CM) after exclusion of coronary artery disease. The authors assessed the diagnostic accuracy of MCG compared with advanced imaging and/or endomyocardial biopsy. The authors enrolled 110 adult patients with angina-like symptoms after exclusion of coronary artery disease from the emergency department, inpatient wards, and outpatient clinics. A total of 220 healthy individuals were incorporated into the study as control subjects by using 1:2 direct matching (age decade and sex) for a total of 330 participants.

MCG detected CM with 94.74% sensitivity (95% CI: 85%-99%), 98.54% specificity (95% CI: 96%-100%), 93.1% negative predictive value (95% CI: 84%-98%), and 94.34% positive predictive value (95% CI: 84%-98%). In 3 patients, cardiac magnetic resonance failed to detect CM, whereas MCG showed pathologic results consistent with results of endomyocardial biopsy. Results were highly reproducible (statistical uncertainty: 2.5%, T-beg-Tmax [interval and electrical vector from the beginning of a T-wave to its peak (MCG score)] ±0.004).

MCG offers a noninvasive, reproducible methodology for rapid and accurate detection of CM after exclusion of ischemic heart disease. Our data indicate that MCG may be an efficient tool for allocation of advanced imaging to those patients with a high likelihood of disease. (Magnetocardiography as a Diagnostic Screening Tool for Myocarditis and Other Types of Cardiomyopathy [MagMa]; NCT06689098).