Multielectrode Unipolar Voltage Mapping and Electrogram Morphology to Identify Post-Infarct Scar Geometry: Validation...

Area of Science:

• Cardiovascular Electrophysiology
• Cardiac Scar Imaging
• Myocardial Ablation Substrate Mapping

Background:

• Endocardial scar after reperfusion is variable and often overlaid by viable myocardium.
• Bipolar voltage (BV) mapping is standard for substrate ablation, but unipolar voltage (UV) mapping's role is less explored.
• Small electrode catheters may improve identification of complex scar geometries.

Purpose of the Study:

• To evaluate uni- and bipolar electrograms from a multielectrode catheter for scar delineation.
• To assess the capability of these electrograms in determining local scar complexity.
• To compare the utility of UV and BV mapping in characterizing myocardial scar.

Main Methods:

• Mapping of 12 swine with early reperfusion infarctions using OctaRay and conventional catheters.
• Acquisition of unipolar and bipolar electrograms during sinus rhythm.
• Histological assessment of 933 transmural biopsy specimens to classify scar geometry.

Main Results:

• UV and BV amplitudes correlated with viable myocardium, with a stronger association for UV (R ² =0.767 vs 0.473).
• UV and BV cutoff values of 3.7 mV and 1.0 mV delineated scar (AUC 0.803 and 0.728).
• OctaRay bipolar electrograms identified double-layered surviving myocardium more frequently than conventional catheters (84% vs 71%).

Conclusions:

• UV mapping with multielectrode catheters can delineate areas of interest for scar characterization.
• Bipolar electrogram morphology within these areas can identify epicardial layers overlying potentially arrhythmogenic endocardium.
• This approach enhances understanding of scar architecture for substrate-based ablation.