Impact of Interelectrode Spacing on Ventricular Tachycardia Substrate Mapping: Insights Into 3-Dimensional Characteristics of the Arrhythmogenic Substrate.

BACKGROUND

Re-entrant ventricular tachycardia (VT) circuits often involve 3-dimensional activation across the endocardium, epicardium, and mid-myocardium, highlighting the importance of comprehensive substrate assessment. Wider interelectrode spacing may incorporate broader-field electrical components that are less apparent on conventional closely spaced recordings.

OBJECTIVES

This study sought to investigate the electrophysiological impact of interelectrode spacing on substrate mapping and its potential implications for 3-dimensional features of VT substrate.

METHODS

Sixty-eight high-density substrate maps from 35 patients undergoing catheter ablation for scar-related VT were retrospectively analyzed. Closely spaced (2-mm) and widely spaced (8-mm) bipolar electrograms were simultaneously acquired using a decapolar catheter and used to generate closely and widely spaced bipolar electrode maps (CEM and WEM).

RESULTS

Compared with CEM, WEM, which incorporates a greater contribution of far-field components, demonstrated higher bipolar amplitudes, a greater prevalence of multicomponent electrograms, and a lower prevalence of split potentials (all P < 0.01). Lines of block delineated by split potentials on CEM were frequently attenuated or no longer apparent on WEM because the corresponding electrograms appeared fragmented and lacked a distinct split configuration. In an exploratory analysis of 6 VTs with evaluable activation maps, activation gaps were larger with closely than widely spaced bipolar mapping (32.5% vs 20.0%; P = 0.03). In 4 VTs, widely spaced recordings identified diastolic or presystolic far-field potentials not evident with closely spaced recordings.

CONCLUSIONS

Widely spaced bipolar electrograms may provide complementary functional information beyond that obtained with conventional near-field recordings by incorporating broader-field electrical components, thereby offering additional insight into the potential 3-dimensional characteristics of the arrhythmogenic substrate.