What does early depolarization in the precordial (electrocardiogram) leads represent?

From the Guidelines

Early depolarization in the precordial leads of an electrocardiogram (ECG) represents a normal variant, but can also be associated with an increased risk of cardiac death and arrhythmias, particularly in individuals with underlying heart conditions or other risk factors, as noted in the 2018 guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death 1.

Key Points

• The early repolarization pattern is characterized by a distinct J point and ST elevation in the lateral or inferolateral leads, with a prevalence of 1-13% in the general population, and is more common in young athletes, particularly African Americans, as reported in the 2017 guideline for the evaluation and management of patients with syncope 1.
• The pattern can be benign, but has also been associated with an increased risk of idiopathic ventricular fibrillation and sudden cardiac death, highlighting the importance of careful evaluation and risk stratification, as discussed in the 2016 scientific statement from the American Heart Association on electrocardiographic early repolarization 1.
• The definition of early repolarization has evolved over time, with current guidelines recommending a standardized definition that includes ST-segment elevation, terminal QRS slurring, or terminal QRS notching, as outlined in the 2016 scientific statement from the American Heart Association 1.
• Clinicians should be aware of the potential risks and benefits associated with early repolarization, and consider further evaluation or treatment in individuals with underlying heart conditions or other risk factors, as recommended in the 2018 guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death 1.

Clinical Implications

• Early depolarization in the precordial leads should be carefully evaluated in the context of the individual patient's medical history, symptoms, and other risk factors, as noted in the 2017 guideline for the evaluation and management of patients with syncope 1.
• Further testing, such as exercise stress testing or cardiac imaging, may be necessary to rule out underlying heart conditions or other risk factors, as recommended in the 2018 guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death 1.
• Treatment options, such as antiarrhythmic medications or implantable cardioverter-defibrillators, may be considered in individuals with early repolarization and underlying heart conditions or other risk factors, as discussed in the 2016 scientific statement from the American Heart Association on electrocardiographic early repolarization 1.

From the Research

Early Depolarization in Precordial Leads

Early depolarization in the precordial leads, also known as early repolarization syndrome, is a phenomenon characterized by an elevation of the J-point and ST-segment elevation, predominantly in the left precordial leads.

• The syndrome is often associated with a benign condition, but recent studies have demonstrated that it can be linked to a considerable risk of life-threatening arrhythmias and sudden cardiac death (SCD) 2, 3.
• Early repolarization characteristics associated with SCD include high-amplitude J-point elevation, horizontal and/or downsloping ST segments, and inferior and/or lateral leads location 2.
• The prevalence of early repolarization syndrome varies between 3% and 24%, depending on age, sex, and J-point elevation being the main determinants 2.
• The electrocardiographic pattern of early repolarization is characterized by elevated, upward, concave ST segments, located commonly in precordial leads, with reciprocal depression in aVR, tall, peaked, and slightly asymmetrical T waves with notch, and slur on the R wave 4.

Risk Stratification

• The risk stratification in asymptomatic patients with early repolarization syndrome still remains a grey area 2.
• Studies have identified electrocardiographic tools to differentiate the "malignant" form of early repolarization pattern from benign early repolarization pattern, including notching or slurring pattern, ST segment after early repolarization, and T-wave morphology 5.
• Early repolarization pattern with notching pattern and horizontal/descendant ST segments was associated with the highest risk of all-cause and cardiovascular deaths 5.

Clinical Implications

• Early repolarization syndrome is a well-recognized idiopathic electrocardiographic phenomenon that shares remarkable cellular, ionic, and electrocardiographic similarities with the Brugada syndrome and idiopathic ventricular fibrillation 6.
• The syndrome has been associated with idiopathic ventricular fibrillation and with cardiovascular mortality in the general population 5, 3.
• Implantable cardioverter-defibrillator implantation and isoproterenol are the suggested therapies in patients with early repolarization syndrome 2.