Electrocardiographic Early Repolarization

QRS interval: What is it? How to measure it?

“…The AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the Electrocardiogram define the QRS as the signal from the earliest onset to the latest offset of the waveform (14). However, recent interest in the "Early Repolarization" (ER) pattern has emphasized the need for standardization of the characterization of the ER pattern at the cost of a persisting ambiguity on the definition of the end of QRS interval (15,16). Hence, the rationale for the choice of the end of the QRS is driven by the quest for reproducibility more than for the determination of the end of the depolarization propagation process.…”

“…Difficulties are even worse when QRS duration is evaluated to better understand the physiology of the propagation of the depolarization through the ventricles. Furthermore, physiological properties may not hold true in presence of diseased myocardium with fibrosis, disarray, and ischemia or in presence of antiarrhythmic drugs(16).…”

Cellular mechanisms underlying the effects of cilostazol, milrinone, isoproterenol and ajmaline on electrographic and arrhythmic manifestations of early repolarization syndrome, and comparative analysis of the cardiac electrophysiological effects of the optical isomers of mexiletine

“…In this regard, it is also noteworthy that there is a significant discrepancy among studies when it comes to the definition of ERP [Patton 2016]: In the sense of earlier and some recent more permissive definitions, the pattern is so frequent in the general population that it is considered to be a benign normal variant of the ECG [Shipley 1936, Wasserburger 1961, Kambara 1976, Mehta 1995, Klatsky 2003, Maury 2013, and most individuals expressing an ERP are still at low risk for sudden arrhythmic death and remain lifelong asymptomatic. This leads us to the main challenge of the syndrome still to resolve: which ER-patients are vulnerable to sudden arrhythmic death and how to deal with those who are not.…”

“…The definition and diagnostic criteria used in this thesis are based on the latest and most comprehensive expert consensus recommendations by Macfarlane et al andAntzelevitch et al [Macfarlane 2015, Antzelevitch 2016]. Although some other studies challenge these approaches to the definition of ERP [Patton 2016], the aforementioned two are aimed at being more focused on the proarrhythmic aspects of ERP and ERS; therefore they are more likely to apply in the clinical practice, where the main challenge and absolute priority is to screen patients vulnerable to life-threatening ventricular arrhythmias.…”

“…[Tikkanen 2011, Rosso 2012, Rollin 2012 ERP emerges in three typical line-ups on the standard 12-lead ECG: It is denoted as Type I if the pattern is displayed in lateral leads. Healthy individuals expressing Type I ERP are reportedly at lower risk for life-threating arrhythmias; moreover, many authors still account it as a benign ECG-variant when followed by an ascending ST segment [Patton 2016 [Tikkanen 2009, Rosso 2012, Rollin 2012.…”