Noninvasive Parameters for Evaluation of Activation Delay in Arrhythmogenic Cardiomyopathy

Abstract

Prolonged electric activation delay between 2 sites in the heart is due to slow conduction, lengthening of conduction pathways, or both. In the presence of unidirectional block and triggers, enhanced delay promotes reentrant circuits as substrate of arrhythmogenesis in various supraventricular and ventricular arrhythmias. This mechanism is well-known in the chronic stage of myocardial infarction and other types of structural heart disease, including arrhythmogenic cardiomyopathy (AC).1–3 Article see p 475 AC can be defined as, ultimately, a structural heart disease, with signs of heart failure preceded in the early stages by electrophysiological alteration that result in electrocardiographic abnormalities and ventricular arrhythmias. AC includes primarily right ventricular, primarily left ventricular, or biventricular abnormalities.4,5 Arrhythmogenic right ventricular dysplasia/cardiomyopathy is well-known nomenclature for the right-sided variant. However, although histopathological and functional predominance of right ventricular abnormalities are frequently found, the left ventricle is affected in most patients as well. Moreover, at the molecular level, both ventricles are affected by altered expression and distribution of intercalated disk proteins.6–8 Because of these considerations, AC has recently become the favored terminology of this group of frequently difficult-to-distinguish disorders. AC is considered a genetic disorder primarily associated with gene mutations encoding desmosomal proteins, although nondesmosomal genes are also involved in a minority, but substantial number of cases.9–11 Accumulating evidence suggests that gene mutation-related changes or distribution of desmosomal proteins give rise to altered expression and distribution of other intercalated disk proteins, including gap junction and ion channel proteins, resulting in mechanical and electric uncoupling …