Magnetocardiography in diagnosis of MINOCA: a case series

Currently, there is a paucity of accurate, convenient, rapid, and efficient diagnostic approaches for myocardial infarction with non-obstructive coronary arteries (MINOCA) in patients who have undergone coronary angiography (CAG) or coronary computed tomography angiography (CCTA) confirming non-obstructive coronary arteries, particularly when the ECG is normal or non-diagnostic. Given that MINOCA is pathologically characterized by myocardial ischemia and abnormal local electrical activity, magnetocardiography (MCG), which can sensitively detect changes in myocardial depolarization and repolarization current density, may provide a promising diagnostic option.

This case series includes 2 patients with non-ST-segment elevation myocardial infarction (NSTEMI), both of whom were confirmed to have a subtype: MINOCA, and all underwent MCG. In both cases, serial ECG findings were normal, yet myocardial enzymes were elevated (suggestive of infarction); thus to resolve this diagnostic ambiguity, we assessed infarction-related waveform features by referencing previously observed infarction characteristics and confirmed that even without ECG-detectable infarction, MCG waveforms still exhibit highly prominent infarction-related features. Subsequent cardiac catheterization confirmed no coronary artery stenosis in both patients. In the second case, cardiac magnetic resonance (CMR) further completed the guideline-specified final diagnostic workflow for MINOCA, which retrospectively validated the diagnostic accuracy of MCG.

In real-world clinical practice, conventional diagnostic pathways frequently face challenges in the underdiagnosis and suboptimal classification of MINOCA. As a rapid, painless, non-invasive, and radiation-free technique, MCG may serve as a complementary functional assessment tool for patients with suspected MINOCA and elevated myocardial biomarkers. Based on these preliminary case observations, MCG shows potential to identify subtle electrical abnormalities related to myocardial ischemia that are not readily captured by routine examinations. This study provides exploratory evidence supporting the possible additive value of MCG in refining the diagnostic workflow of MINOCA, and warrants further larger-scale investigations to validate its clinical utility, including differentiation from other non-ischemic myocardial injury conditions.