Optimizing Interelectrode Distance for Accurate Mapping of Postinfarct Scars: Insights on Electrogram Characteristics.

Background: There is an ongoing effort to develop catheters with closer interelectrode spacing to improve mapping resolution. However, the optimal distance for mapping postinfarct scar has yet to be established.

Objectives: This study sought to assess the effect of interelectrode distance on ventricular scar electrograms.

Methods: In 8 swine with healed myocardial infarction, the left ventricle was mapped using an experimental 48-electrode array with a 1.2 mm center-to-center distance. Additional maps with 2.4, 3.6, and 4.8 mm distances were created using nonadjacent electrodes. The impact of interelectrode distance on voltage amplitude and near-field (NF) and far-field (FF) activity relationships was analyzed.

Results: At a 1.2 mm interelectrode distance, voltage amplitudes <1.5 mV accurately correlated with the endocardial infarct surface area, while increasing the distance to 4.8 mm progressively overestimated the infarct area (P < 0.001). However, adjusting voltage cutoffs for each interelectrode distance restored the correlation to the actual infarct size. The primary distinction between distances was the ability to differentiate NF from FF potentials. At 4.8 mm and 3.6 mm, FF potential amplitude often exceeded NF amplitude (NF/FF ratios of 0.8 ± 0.3 and 0.9 ± 0.2, respectively). Reducing the distance to 2.4 mm attenuated FF potentials, yielding an NF/FF ratio of 1.2 ± 0.4. Further reduction to 1.2 mm showed no significant additional effect (NF/FF ratio 1.3 ± 0.3; P = 0.09).

Conclusions: Bipoles with a 2 mm interelectrode distance most effectively match endocardial scar tissue and attenuate NF potentials. These benefits plateau at 2 mm, suggesting that it may represent the optimal distance for delineating postinfarction substrates.