Magnetocardiographic classification and non-invasive electro-anatomical imaging of outflow tract ventricular arrhythmias in recreational sport activity practitioners.

Ventricular arrhythmias (VAs) with left bundle-branch-block and inferior axis morphology (LBBB-IA), suggestive of outflow tract (OT) origin, are a challenge in sports medicine because they can be benign or expression of a silent cardiomyopathy. Non-invasive classification is essential to plan ablation strategy if required. We aimed to evaluating magnetocardiographic (MCG) discrimination of OT-VAs site of origin (SoO). MCG and ECG data of 26 sports activity practitioners, with OT-VAs were analyzed. OT-VAs-SoO was classified with discriminant analysis (DA) of 8 MCG parameters and with invasively-validated ECG algorithms. MCG inverse source-localization merged with magnetic resonance (CMR) provided three-dimensional electro-anatomical imaging (MCG 3D-EAI). ECG classification was univocal in 73%. MCG-DA differentiated right ventricular OT from aortic sinus cusp VAs, with 94.7% accuracy. MCG 3D-EAI confirmed OT-VAs-SoO in CMR images. In cases undergoing ablation, MCG 3D-EAI was confirmed by CARTO 3D-EAI. MCG-DA improves non-invasive classification of OT-VAs-SoO. Further comparison with interventional results is required.

Unshielded magnetocardiography: Repeatability and reproducibility of automatically estimated ventricular repolarization parameters in 204 healthy subjects.

BACKGROUND: Magnetocardiographic mapping (MCG) provides quantitative assessment of the magnetic field (MF) induced by cardiac ionic currents, is more sensitive to tangential currents, and measures vortex currents undetectable by ECG, with higher reported sensitivity of MCG ventricular repolarization (VR) parameters for earlier detection of acute myocardial ischemia. Aims of this study were to validate the feasibility of in-hospital unshielded MCG and to assess repeatability and reproducibility of quantitative VR parameters, considering also possible gender- and age-related variability. METHODS: MCG of 204 healthy subjects [114 males-mean age 43.4 ± 17.3 and 90 females-mean age 40.2 ± 15.7] was retrospectively analyzed, with a patented proprietary software automatically estimating twelve VR parameters derived from the analysis of the dynamics of the T-wave MF extrema (five parameters) and from the inverse solution with the effective magnetic dipole model giving the effective magnetic vector components (seven parameters). MCG repeatability was calculated as coefficient of variation (CV) ±standard error of the mean (SEM). Reproducibility was assessed as intraclass correlation coefficient (ICC). RESULTS: The repeatability of all MCG parameters was 16 ± 1.2 (%) (average CV ± SEM). Optimal (ICC > 0.7) reproducibility was found for 11/12 parameters (mean values) and in 8/12 parameters (single values). No significant gender-related difference was observed; six parameters showed a strong/moderate correlation with age. CONCLUSION: Reliable MCG can be performed into an unshielded hospital ambulatory, with repeatability and reproducibility of quantitative assessment of VR adequate for clinical purposes. Wider clinical use is foreseen with the development of multichannel optical magnetometry.