The description of the epsilon wave on the electrocardiogram (ECG) by Fontaine and Chen in patients with arrhythmogenic right ventricular dysplasia and the excellent (and correct) observation by Bonny, brings to the clinical forefront the enigma of myocardial repolarization as noted on the standard ECG. The varying characteristics of early repolarization (ER) with reference to the J wave, with and without slurring, and with and without ST-segment elevation are well presented in the report by Bonny.

The most frequent type and occurrence of ER seen on routine ECGs are the so-called “high takeoff” of the ST segments, which are unaccompanied by slurs or notches in the terminal portion of the QRS complex classified as type 5 ER by Heng et al, in their definition of this electrocardiographic phenomenon. The ECG is the most used cardiac test in our diagnostic armamentarium. It concurs with the criteria for ease of use, ready availability, the economy of low cost and has no side-effects or complications—except for those which may be associated with misinterpretation.

Presently, we have several electrocardiographic parameters vying for diagnostic and/or prognostic significance, namely QRS-T angle, QTc interval, signal-averaged ECG, microvolt alternans, and the various forms of ER. Presently, it is the latter that is most enigmatic, and except for microvolt alternans, the others are reasonably pragmatic.

The basic problem facing the clinician and is in the forefront of the early repolarization patterns (ERP) is attempting to decide which is benign (or likely to be benign) versus those which portend present or future morbid events (cardiac dysrhythmia and sudden death). When ERP are associated with obvious pathologic entities such as arrhythmogenic right ventricular dysplasia and apical hypertrophic cardiomyopathy, there are usually distinct abnormalities of repolarization present with an abnormal QRS-T angle and/or deeply negative T waves. The problem of assessing the long-term importance of ERP was further enhanced by the study of Adhikarla et al, which demonstrated that over a period of 10 years, 62% of the study group lost the diagnostic criteria for ER. They concluded that their study supports the long held clinical belief that ER is primarily a benign phenomenon that is seen most often in young, healthy individuals but can occur at any age. Dependent on the particular pattern of ER, it is difficult to determine where depolarization ends and repolarization begins. In some cases, both may influence the electrocardiographic pattern visible on the ECG which we characterize as ER. Perhaps those patterns which contain the “notches” are more ominous with respect to future untoward cardiac events, followed by the “slurs,” and lastly by those exhibiting the smooth, concave, uniformly elevated ST segments without notches or slurs and those with J-point elevation and an ST segment that elevates diagonally from the J point to the beginning of the T wave. This type may sometimes be erroneously confused with an acute current of injury pattern. This opinion gains some credibility by the extensive study of Rollin et al who concluded that there was a higher risk of all-cause death and cardiovascular death in those patients with ERP exhibiting the notch pattern in conjunction with horizontal and/or descendant ST segments. Rosso et al, noted that ER with J-point elevation was more common in patients with idiopathic ventricular fibrillaltion. Evaluation of the QT-interval and signal-averaged ECG in conjunction with the various types of ERP when first diagnosed and during appropriate follow-up as may be indicated, would be of value.

The quest for simple, noninvasive, and inexpensive prognosticators will continue. The aberrancies often noted on the ECG are not present without reason—they have meaning, some of which are of greater significance than others, and just need proper attention and decoding.