A novel Ventricular map of Electrograms DUration as a Method to identify areas of slow conduction for ventricular tachycardia ablation: The VEDUM pilot study

Background: Bipolar electrogram (EGM) duration is indicative of local activation property and, if prolonged, is useful to discover areas of slow conduction favoring arrhythmias.

Objective: The present study aimed to create a map of EGM duration during the ventricular tachycardia (VT) (Ventricular Electrograms DUration as a Method map [VEDUM map]) to verify if the slowest activation area is crucial for reentry and could represent a suitable target for rapid VT interruption during ablation.

Methods: Prospectively 30 patients were enrolled for this study. Twenty-one patients were selected, and 24 VT maps with complete circuit delineation (>90% tachycardia cycle length) were analyzed. Activation and VEDUM maps during VT as well as voltage maps during sinus rhythm were created.

Results: Twenty-two of 24 VTs (88%) were interrupted during the first radiofrequency delivery (mean time 7.3 ± 5.4 seconds; range 3-25 seconds) at the area with the longest EGM duration (212 ± 47 ms; range 113-330 ms). The mean percentage of the cycle length of VT covered by the EGM with the longest duration was 58% ± 12%. In 9 patients (37%), the longest EGM was located at the isthmus entrance, at the exit in 7 maps (30%), and the mid-isthmuses in 8 maps (33%). In 6 patients (25%), the EGM covered the full diastolic phase. The mean isthmus width was 28 ± 11 mm (range 16-48 mm; median 25 mm).

Conclusion: A VEDUM map is highly accurate in defining a conductive vulnerable zone of the VT circuit. The longest EGM duration within the isthmus is highly predictive of rapid VT termination at the first radiofrequency delivery even in the case of large isthmuses.