Does prolonged action potential always indicate greater early-afterdepolarization risk?

Abstract

Prolongation of action potential duration (APD) has been widely believed to be positively associated with, and indeed a trigger of early afterdepolarizations (EADs). In the clinical setting, QT interval prolongation, which indicates underlying prolongation of APD, is an important risk indicator of torsades de pointes (TdP), a ventricular tachyarrhythmia triggered by EADs. However, some studies have shown that positive APD-EAD relationship does not always hold. For example, Alfuzosin and ranolazine prolong QT interval clinically but are not linked to TdP.