(See also Overview of Arrhythmias Overview of Arrhythmias The normal heart beats in a regular, coordinated way because electrical impulses generated and spread by myocytes with unique electrical properties trigger a sequence of organized myocardial... read more and Overview of Channelopathies Overview of Channelopathies Channelopathies are a group of genetic, autoimmune, or inflammatory conditions that alter cardiomyocyte ion channel function in a manner that predisposes to bradyarrhythmias or tachyarrhythmias... read more .)
Early repolarization refers to ECG findings typically including J-point elevation ≥ 0.1 mV, often with a slurred or notched appearance, followed by ST-segment elevation in 2 or more contiguous leads. This ECG pattern is not uncommon, as it occurs in about 5% to 10% of the population, especially in men, younger patients, and athletes. Most people with this early repolarization ECG pattern do not manifest arrhythmias. However, early repolarization is substantially more common in survivors of apparently idiopathic ventricular fibrillation (VF), and early repolarization syndrome refers to people with early repolarization on ECG who also have had symptomatic ventricular arrhythmias. The risk of arrhythmia is higher when the early repolarization pattern is in the inferior leads, the lateral leads, or both.
Early repolarization syndrome appears to result from mutations that produce a
Gain of function of outward potassium current channels OR
Loss of function of inward sodium or calcium current channels
These ion channel changes magnify the normal small transmural voltage gradients during the plateau phase of the action potential. These gradients produce a J-wave and J-point elevation on the ECG and predispose to polymorphic ventricular tachycardia which can degenerate into ventricular fibrillation Ventricular Fibrillation (VF) Ventricular fibrillation causes uncoordinated quivering of the ventricle with no useful contractions. It causes immediate syncope and death within minutes. Treatment is with cardiopulmonary... read more . Prior to the VT/VF the early repolarization pattern may become more exaggerated and the VT/VF may be precipitated by an episode of myocardial ischemia. The polymorphic VT is often initiated by a short-long-short RR interval sequence (although this sequence is not specific for early repolarization syndrome): The first short RR interval is between a baseline beat (usually a normal beat) and a premature beat (usually a premature ventricular beat). The long RR interval is the post–extra-systolic pause and ends with a baseline beat (usually a normal beat). This pause is followed by a short RR interval when the VT begins.
Early repolarization syndrome appears to be inheritable, but disease-specific gene mutations are rarely identified, suggesting that the disorder is often polygenic.
The ventricular arrhythmias may cause palpitations, and/or cardiac arrest. Syncope may occur but is uncommon because VT that occurs with early repolarization syndrome rarely self-terminates (unlike with some other disorders that cause VT in which syncope is more common).
Diagnosis of Early Repolarization Syndrome
Characteristic clinical and ECG manifestations
Clinical screening of first-degree family members
Diagnosis should be considered in patients who have had polymorphic ventricular tachycardia, ventricular fibrillation, or sudden cardiac arrest (or a family history of those events in the absence of structural heart disease) and who also have ECG changes showing an inferior and/or lateral early repolarization pattern. The typical ECG finding of early repolarization is J-point elevation of ≥ 1 mm (≥ 0.1 mV) followed by ST segment elevation in two or more contiguous inferior and/or lateral leads.
Because specific gene defects are seldom identified, genetic testing is not typically recommended for patients or family members. However, first-degree family members should be evaluated clinically and with an ECG.
Treatment of Early Repolarization Syndrome
Implantable cardioverter-defibrillator (ICD) if symptomatic
For asymptomatic patients with the early repolarization ECG pattern and no family history of sudden death, no treatment is recommended because such patients are at very low risk.
Patients who have had cardiac arrest or who have demonstrated VF or polymorphic VT are at high risk and should have an ICD placed. An ICD should be considered for certain patients with the early repolarization ECG pattern and certain other high-risk features (1 Treatment reference Early repolarization syndrome is a genetic disorder of cardiomyocyte ion channel function (channelopathy). Patients are predisposed to polymorphic ventricular tachycardia (VT) and ventricular... read more ).
When frequent ICD discharges need to be suppressed, quinidine, which blocks the outward potassium current that may be increased in early repolarization syndrome, may be efficacious. IV isoproterenol may be useful in patients who have multiple episodes of ventricular arrhythmias in quick succession (electrical storm).
1. Priori SG, Wilde AA, Horie M, et al: HRS/EHRA/APHRS expert consensus statement on the diagnosis and management of patients with inherited primary arrhythmia syndromes: document endorsed by HRS, EHRA, and APHRS in May 2013 and by ACCF, AHA, PACES, and AEPC in June 2013. Heart Rhythm 10:1932–1963, 2013. doi: 10.1016/j.hrthm.2013.05.014
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