Experimental verification of the value of the T-Tinterval in ventricular arrhythmia inducibility in an early repolarization syndrome model.

Abstract

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 T-Tinterval 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&#x2009;=&#x2009;34). The Iagonist NS5806 (8-10&#x2009;&#xb5;M), the calcium channel blocker verapamil (3&#x2009;&#xb5;M) and acetylcholine (2-3&#x2009;&#xb5;M) were used to mimic the disease model. A ventricular arrhythmia induction test was performed. QT, QT, T-T, and T-T/QTwere measured at 15 to 20&#x2009;minutes after the provocative agent infusion. Polymorphic ventricular tachycardias (pVT) developed in 23 of the 34 preparations (67%). The maximal values of T-Tand T-T/QTwere recorded just before pVT induction. At baseline, without the provocative agents, T-Tand T-T/QTwere not different between pVT-induced and pVT-noninduced preparations. The T-Tof the pVT-induced preparations was longer than that of non-induced preparations (58&#x2009;&#xb1;&#x2009;26.8 msec vs 33&#x2009;&#xb1;&#x2009;6.8&#x2009;msec, P&#x2009;<&#x2009;.001). The T-T/QTof pVT- induced preparations was larger than that of noninduced preparations (0.220&#x2009;&#xb1;&#x2009;0.1017 vs 0.128&#x2009;&#xb1;&#x2009;0.0312, P&#x2009;<&#x2009;.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 T-T. CONCLUSION: T-Tpredicted malignant ventricular arrhythmias in early repolarization syndrome models. T-Treflects the repolarization heterogeneity of ventricular myocardium.