Amiodarone's impact on substrate mapping for scar-related ventricular tachycardia: Insights from personalized heart...

Substrate mapping and ablation for scar-related ventricular tachycardia (VT) are often performed with concomitant amiodarone (AMD), which can modify VT inducibility and alter electrogram (EGM) signatures of arrhythmogenic substrate.

This study aimed to evaluate how AMD influences VT inducibility and bipolar EGM markers using heart digital twins.

The effects of AMD at 2 therapeutic concentrations were characterized using heart digital twins incorporating patient-specific ischemic substrate distributions. VT inducibility was tested from multiple sites, and the reentrant circuits were characterized. Identified features of virtual electroanatomic maps included low-voltage, prolonged-duration, high-fractionation EGMs and isochronal crowding (IC) zones. Composite multiple-wavefront pacing maps were used to reduce electroanatomic map dependence on wavefront direction.

AMD did not significantly change overall VT inducibility, although a nonsignificant trend toward fewer inducible sites emerged at higher doses. At the VT circuit level, several baseline circuits disappeared, new drug-associated pathways emerged, and persistent morphologies tended to exhibit longer cycle lengths. AMD broadened regions classified as abnormal by voltage, duration, and fractionation, expanding the apparent substrate and reducing mapping specificity. With a single pacing site, IC zones were within 9 mm of the critical isthmus, more targeted than abnormal signal features, and not appreciably expanded by AMD. Combining multiple pacing orientations markedly improved colocalization without loss of specificity.

Concomitant AMD alters VT morphology and expands abnormal regions identified during substrate mapping, potentially obscuring critical ablation targets. Functional mapping strategies emphasizing IC and incorporating multiple-wavefront directions may improve long-term procedural success of scar-related VT ablation, particularly when AMD cannot be withdrawn.