From the Guidelines
Axis deviation on an ECG is an abnormal direction of the heart's electrical activity, and it is crucial to identify and interpret it correctly to determine the underlying cardiac condition and provide appropriate treatment. The normal cardiac axis falls between -30 and +90 degrees, and any deviation from this range can indicate various cardiac conditions.
- Left axis deviation occurs when the axis is between -30 and -90 degrees, often indicating left ventricular hypertrophy, left anterior fascicular block, or certain congenital heart defects 1.
- Right axis deviation, with an axis between +90 and +180 degrees, may suggest right ventricular hypertrophy, right bundle branch block, pulmonary embolism, or lateral wall myocardial infarction 1. Axis deviation is determined by analyzing the QRS complex patterns in leads I, II, and III. While axis deviation itself doesn't require specific medication, it serves as an important diagnostic clue that should prompt further investigation into underlying cardiac conditions. The finding helps clinicians understand the heart's electrical conduction pattern and may indicate structural or functional abnormalities requiring treatment. In some cases, axis deviation can be associated with an increased risk of cardiac events, and therefore, it is essential to consider it in the context of the patient's overall clinical presentation and medical history 2. It is also important to note that axis deviation can be influenced by various factors, including age, body habitus, and underlying cardiac conditions, and therefore, it is crucial to interpret it in the context of the individual patient's characteristics 1. Overall, accurate identification and interpretation of axis deviation on an ECG are critical for providing appropriate diagnosis and treatment of underlying cardiac conditions.
From the Research
Axis Deviation on ECG
Axis deviation on an electrocardiogram (ECG) refers to an abnormal direction of the electrical axis of the heart. This can be either left axis deviation (LAD) or right axis deviation (RAD).
Causes and Associations
- Left axis deviation is often associated with underlying structural heart disease 3.
- Left anterior fascicular block is one of the commonest causes of left axis deviation and has specific ECG criteria for its diagnosis 3.
- Right axis deviation and left axis deviation can occur in patients with systemic sclerosis-related pulmonary hypertension (SSc-PH), with RAD being associated with predominantly right-sided cardiac disease and increased PH severity 4.
- LAD is associated with predominantly left-sided cardiac disease but is not associated with PH severity on cardiopulmonary hemodynamics 4.
Prognostic Value
- Both RAD and LAD are associated with an increased hazard for all-cause mortality in patients with SSc-PH 4.
- Axis deviation reflects structural cardiac abnormalities and is associated with poor prognosis in patients with SSc-PH 4.
- ECG is an important tool in risk stratification, as it is an inexpensive and widely available noninvasive test 4.
Other Considerations
- There is no direct evidence in the provided studies to suggest that axis deviation is related to adenosine-induced myocardial perfusion heterogeneity or the effects of beta-blockers on adenosine actions 5.