Optimal Annotation of Local Activation Time in Ventricular Tachycardia Substrate Mapping

Area of Science:

• Electrophysiology
• Cardiac Mapping
• Ventricular Tachycardia

Background:

• Accurate local activation time (LAT) annotation is crucial for assessing ventricular tachycardia (VT) substrate.
• Current LAT annotation methods include earliest, peak, latest bipolar electrogram, and steepest unipolar -dV/dt.
• The optimal method for LAT annotation in VT substrate mapping remains unclear.

Purpose of the Study:

• To investigate and compare different LAT annotation methods for VT substrate mapping.
• To determine the most effective method for identifying critical VT re-entry sites.

Main Methods:

• High-density VT substrate maps from 50 patients with defined critical re-entry sites were analyzed.
• Electrograms were annotated using five methods: LAT_earliest, LAT_peak, LAT_latest, LAT_-dV/dt, and LAT_DWOI (steepest unipolar -dV/dt with dynamic window of interest).
• Maps were compared for their ability to identify critical sites using deceleration zones.

Main Results:

• LAT_latest, LAT_earliest, and LAT_peak methods identified critical sites in 100% of cases.
• LAT_-dV/dt identified critical sites in only 54% of cases, and LAT_DWOI in 76%.
• LAT_-dV/dt inaccurately annotated late potentials (33% correct) due to preferential annotation of far-field signals.

Conclusions:

• LAT_-dV/dt and LAT_DWOI are suboptimal for VT substrate mapping.
• LAT_latest is proposed as the gold standard due to its effectiveness in identifying critical sites and suitability for automation.