Effects of pacing sites on substrate mapping using decrement-evoked potential mapping for scar-related ventricular tachycardia

Background and aims The ventricular tachycardia (VT) substrate map is influenced by the rhythm during mapping. This study aimed to elucidate the effects of different pacing sites on substrate mapping using decrement-evoked potential (DEEP) mapping in patients with scar-related VT. Methods Patients with ischemic cardiomyopathy (ICM) or nonischemic cardiomyopathy (NICM) who underwent substrate mapping and ablation for scar-related VT were included. DEEP mapping was performed during right ventricular apex (RVA) and epicardial left ventricular outflow tract (LVOT) pacing. We analyzed the number, location, shape, and timing of lines of conduction block (LOB) using substrate maps obtained during RVA and LVOT pacing. Results A total of 20 patients (age, 62.7 ± 16.6 years; 17 males; 11 with ICM and 9 with NICM) were studied. The number of pacemap-matching LOBs identified from the RVA S1, RVA S2, LVOT S1, and LVOT S2 maps were 0.61 ± 0.70, 1.24 ± 1.09, 1.00 ± 0.85, and 1.50 ± 1.17, respectively. The number of final pacemap-matching LOBs was 1.58 ± 1.07. Two LOBs were visible only during RVA pacing because they were parallel to the conduction direction. Six LOBs were visible only during LVOT pacing—five LOBs were parallel to the conduction direction, and one LOB was located at the wavefront collision area. During a mean follow-up of 9.7 ± 3.3 months, VT recurred in 31.6% of patients. Conclusions A high number of pacemap-matching LOBs on critical substrates can be identified using two-site (RVA and LVOT) pacing DEEP mapping.