Electrogram characteristics in postinfarction ventricular tachycardia: effect of infarct age

Area of Science:

• Cardiology
• Electrophysiology
• Medical Imaging

Background:

• Experimental studies link infarct age to subepicardial electrogram (EGM) duration.
• The relationship between infarct age and endocardial EGM characteristics in postinfarction ventricular tachycardia (VT) patients remains unexplored.

Purpose of the Study:

• To correlate infarct age with endocardial electrogram (EGM) characteristics in patients undergoing mapping for postinfarction ventricular tachycardia (VT).

Main Methods:

• Endocardial left ventricular (LV) mapping was performed in 23 patients with remote infarction and VT using an electroanatomical mapping system during sinus rhythm.
• Analyzed electrogram morphology and width, correlating them with infarct age.
• Identified VT re-entry circuit isthmus sites via entrainment mapping, relating them to substrate mapping results.

Main Results:

• A significant correlation was found between infarct age and bipolar endocardial EGM width in the peri-infarct zone (r = 0.84; p < 0.0001).
• Increasing infarct age correlated with progressive activation delays and isolated potentials, with longer isoelectric intervals (r = 0.77; p < 0.001).
• VT isthmus sites exhibited the most significant delays and broadest EGMs during sinus rhythm.

Conclusions:

• Broad, fractionated EGMs and isolated potentials signify healed myocardial infarction, with EGM width increasing with infarct age.
• Electrophysiological properties of peri-infarct tissue are altered by long-term myocardial remodeling.