Isochronal late activation mapping in ischemic scar VT: an independent validation using intraoperative mapping.

BACKGROUND

VT ablation is often limited by hemodynamic instability. Substrate-based ablation strategy is often useful, and isochronal late activation mapping (ILAM) in sinus rhythm (SR) to identify deceleration zones (DZ) has been reported to be effective.

AIM: We aimed at independently validating ILAM concept using data from comprehensive intraoperative VT mapping.

METHOD: Panoramic simultaneous endocardial intraoperative mapping was performed using a 112 bipolar electrode balloon. The late potentials in SR were mapped in eight isochrones, each of 15-30ms duration and correlated to the diastolic path of induced VT. Deceleration zone was defined as the presence of three or more isochrones within a radius of one centimetre. This equates to 10-20 cm/s of apparent conduction velocity.

RESULT: Twenty-five VTs with complete mapped diastolic path were studied in 12 patients. Diastolic path of 17/25(68%) VTs harboured at least one DZ. Overall, 27 DZ were identified with mean of 2.25 per patient. The average conduction velocity in the DZ was 11 ± 2 cm/s.

CONCLUSION

Conduction slowing identified by isochronal late activation mapping during sinus rhythm colocalized with two-thirds of VT diastolic paths in ischemic heart disease patients.