ECG markers of local but not global increase in dispersion of ventricular repolarization (simulation study)

An increase in local dispersion of repolarization (DOR) may contribute more to arrhythmogenesis as compared to changes of global DOR. The aim of this simulation study was to find ECG markers of local increase in DOR in conditions where global DOR remains normal. In the framework of van Oosterom and Oostendorp ECGSIM model, the local DOR was increased in 10 different ventricular locations by (1) action potential duration (APD) shortening/lengthening both on epi- and endocardium, (2) epicardial APD shortening, and (3) endocardial APD shortening. The simulation cases where the increase in local DOR was accompanied by increase in global DOR were excluded from consideration. T-wave parameters were analyzed in the simulated precordial and anatomically ordered limb leads. The increase in local DOR resulted in increased lead-to‑lead differences in Tpeak and Tend instants in 28 out of 32 simulated scenarios, and in an increased dispersion of Tpeak-Tend interval throughout 12 standard leads in 8 out of 32 simulated scenarios. In all simulations, the global DOR measured as a difference between earliest and latest repolarization times and standard APD deviation was the same. The local increase in DOR was expressed in increased lead-to‑lead differences in Tpeak and Tend instants between adjacent anatomically ordered standard leads (aVL, I, aVR(−), II, aVF, III, and V1-V6), even if global DOR, Tpeak-Tend interval and Tpeak-Tend dispersion were within a normal range. •Local and global DOR have probably different roles in arrhythmogenesis.•ECG markers for local and global DOR may be confused.•In our simulations, we set an increased local DOR with the global DOR unchanged.•Tpeak and Tend instants differed across precordial and frontal plane leads.•Tpeak and Tend differences between anatomically adjacent leads express the local DOR.