The early repolarization pattern has long been considered as a benign variant of normal observed predominantly in young, athletic, black and male patients with a tendency to disappear on exertion. It is characterized by a slurring or notching of the terminal portion of the QRS, with a rise of the J point greater or equal to 1 mm above the baseline and ST segment elevation. While the prognosis appeared unchanged, recent studies have suggested a direct relationship between this pattern and an increased risk of sudden death.
The characteristic ECG of early repolarization includes:
- a diffuse concave elevation (pattern similar to that of a smiley), predominant in the mid and left lateral precordial leads but which can also be observed in the inferior leads, generally less than 2 mm even though amplitudes of 5 mm are occasionally observed; the early repolarization pattern is labile and influenced by the autonomic nervous system and the fluctuations in heart rate (tends to increase during a slowing of the heart rate and to regress or even disappear in the presence of tachycardia) ; the depression also tends to decrease with age and is a rare occurrence over 70 years of age;
- there is no reciprocal depression with the exception of the aVR lead;
- an elevation of the J point at the junction between the QRS-complex and the T-wave, with a notch or slur in at least two contiguous leads; the notch can be well individualized in the inferior leads but is often maximal in V4;
- the T-waves are often tall, asymmetrical and concordant with the QRS-complex; the descending branch is more abrupt than the ascending branch, which produces a "hammock" pattern;
- the QRS-complexes are generally normal with a transition zone that is sometimes precocious and deviated to the right with a relatively large amplitude;
The differential diagnosis with a tracing of pericarditis can sometimes be difficult. Indeed, in both cases, a diffuse concave elevation can be observed. Elements suggestive of an early repolarization are the presence of an elevation limited to precordial leads, tall T-waves with notching or slurring of the ST segment-T-wave junction and absence of PQ segment depression.
The benign nature was recently challenged with evidence a higher prevalence of early repolarization among survivors of ventricular fibrillation and an increased cardiovascular mortality in patients with early repolarization. Different factors were found to be more often associated with early so-called "malignant" repolarization: family history of sudden death, personal history of syncope, elevated J wave amplitude, slurred J wave pattern, presence in inferior leads, dynamic pattern of the J wave (increased during a post-extrasystolic pause).