From the Guidelines
The ECG interpretation showing sinus arrhythmia, vertical axis, and ST elevation due to a repolarization variant is considered a normal variant of ECG, and does not indicate cardiac pathology requiring intervention or treatment. This interpretation is based on the latest guidelines and recommendations from the American Heart Association and the American College of Cardiology, as outlined in the 2021 guideline for the evaluation and diagnosis of chest pain 1. Sinus arrhythmia is a common finding where the heart rate varies with the respiratory cycle, increasing during inspiration and decreasing during expiration. A vertical axis refers to the direction of electrical activity in the heart and is a normal finding in many individuals. ST elevation due to repolarization variant (also known as early repolarization) is a benign finding characterized by ST segment elevation in certain leads, particularly in young, healthy individuals.
The 2009 recommendations for the standardization and interpretation of the electrocardiogram provide further guidance on the evaluation of ST elevation, noting that it can be attributed to a normal variant, injury currents associated with acute ischemia or ventricular dyskinesis, or injury currents usually associated with pericarditis 1. However, in this case, the ST elevation is attributed to a repolarization variant, which is a normal finding.
Key points to consider in the interpretation of this ECG include:
- Sinus arrhythmia is a common and benign finding
- Vertical axis is a normal finding in many individuals
- ST elevation due to repolarization variant is a benign finding, particularly in young, healthy individuals
- The latest guidelines and recommendations from the American Heart Association and the American College of Cardiology should be followed in the evaluation and diagnosis of chest pain 1.
Overall, the ECG interpretation shows normal variants and does not indicate cardiac pathology requiring intervention or treatment.
From the Research
Interpretation of ECG Findings
The interpretation of an electrocardiogram (ECG) showing sinus arrhythmia, vertical axis, and ST elevation due to a repolarization variant can be complex.
- Sinus arrhythmia is a normal variant of ECG, characterized by a variation in the interval between heartbeats 2, 3.
- A vertical axis on an ECG is also a normal finding, indicating the direction of the electrical activity of the heart.
- ST elevation, however, can be a sign of various conditions, including myocardial infarction, pericarditis, and repolarization variants 4, 5, 6.
Repolarization Variants
Repolarization variants, such as early repolarization, can cause ST elevation on an ECG.
- Early repolarization is characterized by an elevation of the QRS-ST junction (J point) ≥ 2 mv from baseline in the inferior or lateral leads, manifested as QRS slurring or notching 2.
- This condition was previously considered a benign ECG variant but has recently been associated with an increased risk of sudden cardiac death, particularly in individuals with certain high-risk features such as male gender, history of syncope or sudden cardiac death in family, and terminal notching of QRS complex 2, 3.
Differentiation from Other Conditions
It is essential to differentiate repolarization variants from other conditions that can cause ST elevation, such as ischemic ST elevation and non-ischemic ST elevation.
- Ischemic ST elevation is typically associated with reciprocal ST depression, ST-segment convexity, and terminal QRS distortion, whereas non-ischemic ST elevation may show PR depression, ST-segment concavity, and no terminal QRS distortion 5.
- Pulmonary embolism can also present with ST elevation, although this is rare, and the ECG findings may be non-specific 6.
Clinical Implications
The clinical implications of an ECG showing sinus arrhythmia, vertical axis, and ST elevation due to a repolarization variant depend on the individual's symptoms, medical history, and other diagnostic findings.
- In asymptomatic individuals with no high-risk features, early repolarization may be considered a normal variant 2, 3.
- However, in individuals with symptoms such as syncope or palpitations, or those with high-risk features, further evaluation and management may be necessary to prevent sudden cardiac death 2, 3.