Early Repolarization Pattern Revisited

The American Heart Association just released a Scientific Advisory entitled “Electrocardiographic Early Repolarization” (ER).¹ This statement, drafted by leading experts in the field of electrocardiology, provides an insightful review of the state of the art and state of confusion in the field, with thoughtful recommendations for standardization of terminology regarding the early repolarization pattern. The document is expertly crafted and follows on the heels of another consensus statement on ER pattern recently published by Macfarlane et al in the Journal of the American College of Cardiology.²

The confusion stems from considerable differences in the definition of ER in recent population-based and case-control studies as well as consensus statements including those from the 1985 Common Standards of Electrocardiography (CSE, 1985),³ the 2009 AHA/ACCF/HRS ECG standardization document,⁴ and the Macfarlane et al statement.²

Patton et al¹ propose as a definition that “Early Repolarization be considered an umbrella term that can mean any of the following: ST elevation in the absence of chest pain, terminal QRS slurring, or terminal QRS notching, and that studies that use the term ER should clearly state which of these electrocardiogram (ECG) patterns are being used.” They also propose that if the term J-wave, initially used by Osborn to refer to notching at the end of the QRS during experimental hypothermia,⁵ is used to refer to the presence of notches and/or terminal QRS slurs, and that it be further defined using terminal QRS slur and notch terminology. In contrast Macfarlane et al² proposed that Jo, Jp, and Jt, respectively, be used to denote the onset, peak, and termination of the terminal QRS notch or J wave.

The appearance of prominent J waves in the ECG has been reported in a number of pathologies, including hypothermia^6-8 and hypercalcemia.^9,10 In recent years, prominent J waves have been associated with life-threatening ventricular arrhythmias, including the Brugada (BrS) and early repolarization (ERS) syndromes, which are referred to as the J-wave syndromes.¹¹ In humans and some animal species, the normal J wave typically appears as a JO elevation, with part of the J wave buried inside the QRS. An early repolarization pattern in the ECG, consisting of a distinct J wave, JO or Jt elevation, a notch or slur of the terminal part of the QRS, and an ST-segment elevation, has traditionally been viewed as benign.^12,13 The benign nature of an ER pattern was challenged in 2000¹⁴ on the basis of experimental data. The appearance of an ER pattern on the ECG was found to be associated with the development of polymorphic ventricular tachycardia and fibrillation (VT/VF) in coronary-perfused wedge preparations.^11,14-16 Validation of this hypothesis was provided 8 years later by Haïssaguerre et al,¹⁷ Nam et al,¹⁸ and Rosso et al.¹⁹ These formative studies together with numerous population-based and case-control studies provided evidence for an increased risk for life-threatening arrhythmic events and sudden cardiac death among patients displaying an ER pattern, particularly in inferior and infero-lateral leads.

Early repolarization pattern (ERP) is often encountered in seemingly healthy individuals, particularly in young black individuals and athletes. When associated with ventricular tachycardia and ventricular fibrillation in the absence of organic heart disease, ERP is referred to as early repolarization syndrome (ERS).

ERS and BrS are both associated with a risk for development of polymorphic ventricular tachycardia and ventricular fibrillation leading to sudden cardiac death^11,17,18,20 and occasionally to sudden infant death syndrome.^21-23 The region of the heart most affected in BrS is the anterior right ventricular outflow tract; in ERS it is the inferior region of the left ventricle.^17,19,24-28 BrS is characterized by accentuated J waves, appearing as a coved-type ST-segment elevation in the right precordial leads, V1-V3; whereas ERS is characterized by J waves, Jo elevation, notch or slur of the terminal part of the QRS and ST-segment, or Jt elevation in the lateral (type I), infero-lateral (type II), in infero-lateral + anterior, or right ventricular leads (type III).¹¹

The need to properly identify individuals at risk derives from the high prevalence of an ER pattern in the general population. An ER pattern in the inferior and/or lateral leads with a JP elevation of =0.1 mV ranges between 1% and 24%, and for JP elevation of >0.2 mV ranges between 0.6% and 6.4%.^29-31

The lack of agreement regarding the terminology relative to ER has in the past led to a great deal of confusion and inconsistency in reporting,^32-34 which will hopefully greatly diminish with the implementation of the recommendations of the 2 recent consensus reports,^1,2 permitting a more rational approach to risk stratification and treatment.