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Noninvasive Mapping of PVCs by Merging MCG and CT
Study Questions:
What is the predictive ability of a novel premature ventricular contraction (PVC) mapping method to predict PVC origins in whole ventricles by merging a magnetocardiography (MCG) image with a cardiac computed tomography (CT) image?
Methods:
The investigators included 22 candidates referred for catheter ablation of idiopathic PVCs. MCG and CT were performed the same day before ablation. Estimated origins by MCG-CT imaging using the recursive null steering spatial filter algorithm were compared with origins determined by electroanatomic mapping (CARTO, Biosense Webster, Inc., Diamond Bar, CA) during the ablation procedure. Radiopaque acrylic markers for the CT scan and coil markers generating a weak magnetic field during MCG measurements were used as reference markers to merge the two images three-dimensionally.
Results:
PVC origins were determined by endocardial and epicardial mapping and ablation results in 18 (86%) patients (right ventricular outflow tract in 10 patients, aortic sinus cusp in two patients, interventricular septum in one patient, near His bundle in one patient, right ventricular free wall in one patient, and left ventricular free wall in three patients). Estimated origins by MCG-CT imaging matched the origins determined during the procedure in 94% (17 of 18) of patients, whereas the electrocardiography algorithms were accurate in only 56% (10 of 18). Discrimination of an epicardium versus an endocardium or right- versus left-sided septum was successful in three of four patients (75%).
Conclusions:
The authors concluded that diagnostic accuracy of noninvasive MCG-CT mapping was high enough to allow clinical use to predict the site of PVC origins in the whole ventricles.
Perspective:
This small study reports that a novel method to merge the MCG map with the CT image using custom-made markers worked successfully and identified the sites of origin in patients with PVCs originating from both ventricles. From the theoretical and mathematical viewpoints, this technology may have the potential to identify transmural distribution of sites of PVC origin (epicardial vs. endocardial origin and right-sided vs. left-sided septal origin). Additional larger studies are indicated to assess whether this technology improves procedural outcomes, procedural efficiency, and the safety of catheter ablation for ventricular arrhythmias.
Clinical Topics: Arrhythmias and Clinical EP, Noninvasive Imaging, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Computed Tomography, Nuclear Imaging
Keywords: Arrhythmias, Cardiac, Bundle of His, Catheter Ablation, Diagnostic Imaging, Electrocardiography, Endocardium, Epicardial Mapping, Magnetocardiography, Pericardium, Sinus of Valsalva, Tomography, Tomography, Emission-Computed, Ventricular Premature Complexes
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