1.What is early repolarization
Past diagnoses of premature repolarization ECG changes include an elevated J wave or elevated posterior portion of the J point with an elevated ST segment that is bowed back and down. It may also be accompanied by a series of changes such as elevated and tangential R waves and hyperacute T waves.
The modern concept of early repolarization wave includes only J wave or elevation. 2013 international expert consensus defines early repolarization wave as a diagnosis when there are ≥2 consecutive leads (inferior or lateral wall leads) with J point elevation ≥1 mm in a standard 12-lead ECG, and this definition does not mention ST segment elevation.
In addition to the different views on the characteristics of ECG changes, there is also a fundamental change in the leads where the premature repolarization wave appears. The traditional concept is that the premature repolarization wave mainly appears in the mid-thoracic V3 and V4 leads, while the modern view is that the premature repolarization wave appears in the inferior wall (II, III, aVF) and lateral wall (V4~V6, Ⅰ, aVL) leads.
2.The danger of early repolarization
The traditional concept is that early repolarization wave is mostly seen in male young adults, athletes and black people, therefore, it belongs to the normal variation of ECG and is a benign manifestation of ECG.
The modern view is that the risk of sudden cardiac death is 3-10 times higher in those with early repolarization waves compared to those without them, which is a possible adverse prognostic ECG manifestation.
The detection rate of early repolarization in children is relatively high, and it is not relevant if it disappears with age, but if it does not disappear, it should be followed up closely.
3.Population of early repolarization
(1) General population: The detection rate of modern early repolarization waves in the general population is 1% to 13%, and the span of detection rate is still large in different literature.
(2) In the idiopathic ventricular fibrillation population: the detection rate of ECG premature repolarization waves is as high as 15% to 70% in this particular population.
(3) In patients with Brugada syndrome: In about 10% to 15% of patients with Brugada syndrome, coexisting electrocardiographic premature repolarization waves are altered, suggesting that the two can overlap.
(4) Relationship with age: Early repolarization waves on ECG are more common in pediatric patients, but the detection rate of early repolarization waves gradually decreases from early to middle adulthood, and this phenomenon suggests that there is a certain influence of hormones on early repolarization waves.
(5) Gender differences: There are obvious gender differences in the detection of early repolarization waves in ECG, about 70% of the patients with early repolarization waves are male and 30% are female.
4.How to diagnose early repolarization
The diagnosis includes two parts: premature repolarization wave and premature repolarization syndrome.
Diagnosis of early repolarization wave
The diagnosis of premature repolarization wave is simple and easy: that is, it can be diagnosed when there are ≥ 2 consecutive lower or lateral wall leads with J-point elevation ≥ 1mm on 12-lead ECG.
(1) Premature repolarization wave is often accompanied by bradycardia, prolongation of QRS wave time frame, QT shortening and left ventricular hypertrophy.
(2) Exercise test: In order to determine the existence of early repolarization wave, the patient can be made to do various exercise tests, because Ito current and early repolarization wave have long interval (or slow frequency) dependence, when the patient exercise heart rate accelerated, the disappearance of early repolarization wave can determine the diagnosis.
(3) Holter examination: To determine whether the early repolarization wave is accompanied by slow frequency dependence, Holter examination should be performed on the patient. Once catching the own atrial premature and ventricular premature, the change of J wave amplitude after the long RR interval formed during the compensatory period after premature beats needs to be observed, and when the J wave amplitude increases significantly, it helps to confirm the diagnosis and prognosis.
(4) Excitation test: There is no mature excitation test for premature repolarization wave. It is suggested that the heart rate can be slowed down by forceful inspiration or exhalation with Valsalva action, which can help to detect potential premature repolarization wave.
(5) Heart rate elevation method: Early repolarization waves at the end of the QRS wave tend to be staccato or tangential waves, but these early repolarization waves are sometimes difficult to distinguish from QRS fragmentation waves. Recently, Japanese scholar Aizawa proposed to apply the early beat method or the increased heart rate method to observe the change of the wave amplitude, and then make the diagnosis and differentiation between the two.
The test can be performed in the natural state when the patient has his own atrial premature and downwardly excited ventricle (the QRS wave is the same as the sinus rhythm QRS wave), and can also cause an artificial atrial premature by distributing S2 extrasystoles to the atria of the subject dog by means of cardiac electrophysiology, and capture the atria and downwardly excited ventricle (the QRS wave formed is the same as the sinus rhythm), and finally make the QRS wave appear early, then we can observe The response of this wave to the fast frequency (short RR interval) can be observed. In addition to the “early beat method”, the pacing atria can be stimulated with a high-frequency continuous atrial stimulus to observe the change in QRS wave pattern at the end of the wave when the frequency is accelerated.