Experimental verification of the value of the Tpeak -Tend interval in ventricular arrhythmia inducibility in an early repolarization syndrome model.

INTRODUCTION: In patients with early repolarization patterns on ECG, many researchers have studied to find predictors of fatal arrhythmia. However, there are no satisfying clinical predictors. We evaluated the value of the Tpeak -Tend interval on pseudo-ECG in canine myocardial wedge preparation models of early repolarization syndrome.

METHODS AND RESULTS: Transmural pseudo-ECG and endocardial/epicardial action potentials were recorded from coronary-perfused canine left ventricular wedge preparations (n = 34). The Ito agonist NS5806 (8-10 µM), the calcium channel blocker verapamil (3 µM) and acetylcholine (2-3 µM) were used to mimic the disease model. A ventricular arrhythmia induction test was performed. QTpeak , QTend , Tpeak -Tend , and Tpeak -Tend /QTend were measured at 15 to 20 minutes after the provocative agent infusion. Polymorphic ventricular tachycardias (pVT) developed in 23 of the 34 preparations (67%). The maximal values of Tpeak -Tend and Tpeak -Tend /QTend were recorded just before pVT induction. At baseline, without the provocative agents, Tpeak -Tend and Tpeak -Tend /QTend were not different between pVT-induced and pVT-noninduced preparations. The Tpeak -Tend of the pVT-induced preparations was longer than that of non-induced preparations (58 ± 26.8 msec vs 33 ± 6.8 msec, P < .001). The Tpeak -Tend /QTend of pVT- induced preparations was larger than that of noninduced preparations (0.220 ± 0.1017 vs 0.128 ± 0.0312, P < .001). The transmural and epicardial dispersion of repolarization of pVT-induced preparations were larger than those of pVT-noninduced preparations. The transmural dispersion of repolarization showed a positive correlation with Tpeak -Tend .

CONCLUSION: Tpeak -Tend predicted malignant ventricular arrhythmias in early repolarization syndrome models. Tpeak -Tend reflects the repolarization heterogeneity of ventricular myocardium.