High-Resolution Measurement of Local Activation Time Differences From Bipolar Electrogram Amplitude.

Area of Science:

• Electrophysiology
• Cardiovascular Research
• Biomedical Engineering

Background:

• Localized changes in myocardial conduction velocity (CV) are pro-arrhythmic.
• High-resolution mapping of local CV is limited by the temporal resolution of clinical methods.
• Accurate measurement of local activation time (LAT) differences at small spatial scales (1 mm) requires high temporal resolution (≤1 ms).

Purpose of the Study:

• To develop a novel method for high-resolution measurement of LAT differences.
• To validate the new method against existing techniques using computational models and clinical data.

Main Methods:

• Developed the Determination of EGM Latencies by Transformation of Amplitude (DELTA) method, relating LAT differences to bipolar electrogram (EGM) peak amplitude.
• Validated DELTA using simulated EGMs from computational models with varying complexity (1D, 2D, fibrosis).
• Applied DELTA to 18,740 bipolar EGMs from 10 atrial fibrillation patients undergoing catheter ablation.

Main Results:

• DELTA achieved higher accuracy (3.8% mean error) than standard LAT annotation (22.9% mean error) for LAT differences < 4 ms with 1 kHz sampling.
• CV calculations were more accurate using DELTA-derived LAT differences in simulated models.
• Clinical validation showed agreement between DELTA, standard LAT annotation, and unipolar waveform cross-correlation for LAT differences.

Conclusions:

• The DELTA method leverages the relationship between bipolar EGM peak amplitude and LAT differences.
• DELTA improves the accuracy of measuring small LAT differences, enabling higher-resolution CV measurement.
• This technique has potential clinical applications for improving electrophysiology mapping and understanding arrhythmias.