Effects of Right and Left Ventricular Pacing for Substrate Mapping Using Decrement-Evoked Potential Mapping in Patients with Scar-Related Ventricular Tachycardia

BackgroundThe 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. MethodsPatients 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 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. ResultsA total of 19 patients (mean age, 62.7 {+/-} 16.6 years; 17 males; 10 with ICM and 9 with NICM) were studied. DEEP mapping during RVA and LVOT pacing was performed in 16 patients. 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 7.6 {+/-} 3.9, VT recurred in 26.3% of patients. ConclusionA high number of LOBs on critical substrates can be identified using two-site pacing DEEP mapping.