Abstract 12715: Magnetocardiography can Identify Abnormal Left Intraventricular Conduction Possibly Associated with Future Ventricular Arrhythmias in Non-ischemic Dilated Cardiomyopathy Patients with Normal SAECG
Backgrounds: Signal-averaged electrocardiogram (SAECG) is a valuable non-invasive tool for detecting arrhythmogenic substrates underlying reentry arrhythmia. However, theoretically, this technique must be of limited value when arrhythmogenic substrates (late potential, LP) reside in the early to mid portion of QRS: LP would be buried within QRS, leading to a false negative result. Multi-channel magnetocardiography (MCG) with high spatio-temporal resolution may overcome this limitation and sensitively disclose abnormal LV intraventricular conduction (fragmented LV conduction, fLV) associated with future ventricular arrhythmic events (AE). We examined this hypothesis in non-ischemic dilated cardiomyopathy (NIDCM) without LP on SAECG (normal SAECG).
Methods: We recorded 64ch MCGs to derive QRS current arrow maps and vector magnitude waveforms (VMW) in 40 NIDCM with narrow QRS (LVEF; 26±6%, QRS duration; 100±12ms). LP was not identified in all patients. fLV on MCG was defined when both abnormal discrete components on VMW (>20% of Max amplitude) and heterogeneous LV conduction on QRS mapping were correspondingly recognized. We followed the occurrence of arrhythmic events (sudden death: SCD and sustained VT or VF).
Results: fLV was recognized in 20 (Group-F) but not in 20 (Group-N). Age, gender, ECG and echocardiographic findings, laboratory data and medications at baseline were all comparable between the groups. During a mean follow-up of 2 years, AE occurred in 12 (SCD in 3, VT/VF in 9). Kaplan-Meier event-free analysis revealed that AE more frequently occurred in Group-F (50%, 10/20) than Group-N (10%, 2/20, p=0.01). Multivariate analysis revealed fLV as an independent predictor of AE (HR 4.20, p=0.04).
Conclusions: MCG analysis is a promising noninvasive tool for sensitively disclose abnormal LV intraventricular conduction in NIDCM with normal SAECG. This finding may be useful to predict future ventricular arrhythmic events.
- © 2013 by American Heart Association, Inc.