Repolarization Heterogeneity in Human Post-Infarct Ventricular Tachycardia

Area of Science:

• Cardiology
• Electrophysiology
• Cardiac Arrhythmias

Background:

• Post-infarction ventricular tachycardia (VT) is associated with slow conduction, attributed to fibrosis and connexin remodeling.
• Re-entrant circuits in VT are linked to significant repolarization heterogeneity, as observed in a porcine model due to altered potassium channel activity.

Purpose of the Study:

• To investigate the association between re-entrant circuits in human post-infarction VT and repolarization heterogeneity.

Main Methods:

• Left ventricular mapping was conducted in 6 patients during induced VT to identify VT circuit sites.
• Unipolar mapping using an ablation catheter characterized activation-recovery intervals (ARIs) as surrogates for action potential durations.
• ARIs were compared between sites within the VT circuit isthmus (IN) and infarct scar regions outside the circuit (OUT).

Main Results:

• ARIs were significantly shorter in the IN sites compared to the OUT sites (420.2 ± 79.3 ms vs 462 ± 52.8 ms; P = 0.01).
• All patients exhibited shorter ARI values at VT circuit sites compared to adjacent regions.

Conclusions:

• VT circuit sites in human post-infarct VT are associated with repolarization heterogeneity, mirroring findings in a porcine model.
• This suggests a conserved mechanism for post-infarction VT across species.
• Targeting repolarization kinetics through ablation, small molecules, or gene therapy may offer novel antiarrhythmic strategies.