3297Inverse magnetocardiographic imaging to assess electrical dyssynchrony in heart failure patients

Background: There have been numerous studies focusing on the assessment of left ventricular mechanical and electrical dyssynchrony. It is useful for the exploration of disease mechanism, selection of treatment, risk stratification and prediction of treatment response especially in heart failure (HF) patients, who are eligible for cardiac resynchronization therapy. Using non-invasive methods such as inverse Magnetocardiographic (MCG) imaging provides useful and unique equipment to evaluate the electrical function of the heart based on the estimation of the time evolution of current density (CD) variables map and can assess differences in the temporal distribution of the electrical activation across the ventricular walls. We aimed to clarify the potential of inverse MCG imaging analysis to be used as a tool for the detection of electrical dyssynchrony in HF patients. Methods: 22 patients with symptomatic HF (age 65.3±2.7 years; ejection fraction ≤40% and QRS interval ≥120 ms) with a left bundle branch block and contractile dyssynchrony were retrospectively identified. 22 healthy subjects served as control group. All subjects underwent a complete clinical examination and 9-channel MCG recordings in non-shielded MCG laboratory. Inverse MCG imaging at each time instant was computed for the whole duration of the heartbeat and mapped to the clinically used two-dimensional bulls-eye plots to facilitate subject-to-subject comparisons. The spatial depolarisation dispersion was automatically defined as the time interval from the earliest QRS-wave end to the latest QRS-wave end by using the time evolution of CD variables map. A temporal difference between the earliest and the latest peaks of CD signal was defined as a MCG marker of electrical dyssynchrony.