Bence Patocskai et al. JACEP 2017;3:353-363 Tpeak-Tend Interval and Dispersion of Repolarization Recorded at Each Step of Epicardial Ablation Experiments in the 2 Models (A) Addition of the provocative agents, either NS5806 + verapamil (NS + Ver; n = 6) or pinacidil + ajmaline (Pin + Ajm; n = 4), significantly increased, whereas radiofrequency ablation of epicardium significantly reduced Tpeak-Tend intervals. (B) Addition of the provocative agents significantly increased but epicardial ablation significantly reduced both TDR and EDR. Dark colors represent EDR, pale colors represent TDR. The highest Tpeak-Tend values were associated with the most pronounced delay of the second action potential upstroke giving rise to negative T waves and appeared just before the start of arrhythmic activity. ∗p < 0.01 vs. control. †p < 0.01 vs. pre-ablation. ‡p < 0.001 vs. control. §p < 0.001 vs. pre-ablation. ‖p ≤ 0.015 vs. control. ¶p ≤ 0.028 vs. pre-ablation. EDR = epicardial dispersion of repolarization; TDR = transmural dispersion of repolarization; Tpeak-Tend = interval between the peak and the end of the T-wave. Bence Patocskai et al. JACEP 2017;3:353-363 2017 American College of Cardiology Foundation