Abstract 14750: Imaging Of Myocardial Substrate Of Right Ventricular Tachycardia: Endocardial Voltage Mapping Versus Contrast-enhanced Cardiac Magnetic Resonance.
Purpose: Endocardial voltage mapping (EVM) is currently used for substrate-based mapping and catheter ablation of ventricular tachycardia (VT) in patients with arrhythmogenic right ventricular (ARVC). Contrast-enhanced-cardiac magnetic resonance (CE-CMR) is a competing technique for ventricular tissue characterization, although its ability to identify RV scar underlying VT remains to be established. The aim of the study was to compare EVM and CE-CMR for imaging RV scar lesions in ARVC patients undergoing VT catheter ablation.
Methods: 23 consecutive ARVC (16 males; mean age 38±12 years) referred for management of VT. All patients underwent CE-CMR and intracardiac electrophysiological study including EVM for imaging RV scar and related VT. Catheter ablation was performed during VT and/or at sinus rhythm by creating linear lesions leading to interruption of VT reentry circuit.
Results: The mean number of RV sites sampled by EVM was 172±19. Twenty-one of 23 (91.3%) ARVC patients had an abnormal RV EVM showing ≥1 (mean, 2.29±0.6) electroanatomic scar (EAS), i.e. low-voltage (<0.5mV) areas. Overall, 45 RV EAS were identified: infero-basal (n=17; 38%), antero-lateral (n=12;26.6%), RV outflow tract (RVOT) (N=8;17.7%) and apex (N=8;17.7%). RV delayed contrast enhancement (DCE) was detected in 9 of 23 (39%) patients with a total of 23 RV DCE scars. There was a mismatch between RV EVM and CE-CMR in 24 RV scars, with 22 EAS not confirmed by DCE (13/22 in the infero-basal region). Programmed ventricular stimulation induced a total of 16 VT morphologies in 13 of 23 (56%) patients, whose the reentry circuit was localized in infero-basal (n=10), antero-lateral (n=3), RVOT (n=2) and the apical region (n=1). In all patients, the best VT pace-mapping was obtained from RV sites of the EAS. Acute success of catheter ablation was achieved in 11 of 16 (69%) VTs, with 8 of 11 successfully ablated VT originating from the inferobasal EAS which were undetected by CE-CMR.
Conclusions: EVM allows an accurate identification of RV EAS underlying VT in ARVC patients and support its clinical use for substrate-based mapping and catheter ablation. Currently available CE-CMR appears to visualize RV scars unsatisfactorily and this limits its usefulness to guide interventional RV procedures.
- © 2011 by American Heart Association, Inc.