A high-definition mapping catheter has been introduced, allowing for bipolar recording along and across the spline with a rapid assessment of voltage, activation, and directionality of conduction. We aimed to evaluate differences in mapping density, accuracy, time, and consequently RF time between different mapping catheters used for ventricular tachycardia (VT) ablation. We enrolled consecutive patients undergoing VT ablation at our center. Patients were divided into the LiveWire 2-2-2 mm catheter (group A) and the HD Grid SE (group B). Primary endpoints were total RF delivery time, the number of points acquired in sinus rhythm and VT, and the scar area. Fifty-one patients were enrolled, 22 in group A and 29 in group B. More points were acquired in the Grid group in sinus rhythm (SR) and during VT (2060.78 ± 1600.38 vs. 3278.63 ± 3214.45, p = 0.05; 4201.13 ± 5141.61 vs. 10,569.43 ± 13,644.94, p = 0.02, respectively). The scar area was smaller in group B (Bipolar area, cm² 4.52 ± 2.72 vs. 2.89 ± 2.81, p = 0.05. Unipolar area, cm² 7.47 ± 4.55 vs. 5.56 ± 2.79, p = 0.03). Radiofrequency (RF) time was shorter in the Grid group (30.52 ± 13.94 vs. 22.16 ± 11.03, p = 0.014). LPs and LAVAs were eliminated in overall >93% of patients. No differences were found in terms of arrhythmia-free survival at follow-up. In conclusion, the use of a high-definition mapping catheter was associated with significantly shorter mapping time during VT and RF time. Significantly more points were acquired in SR and during VT. During remap, we also observed more LAVAs and LPs requiring further ablation.