From the Research
Northwest axis deviation on the ECG is a significant finding that indicates an abnormal cardiac electrical axis between -90 and -180 degrees, and it should prompt immediate clinical correlation and further diagnostic testing due to its association with serious underlying cardiac pathology, as seen in a study published in 2025 1. This pattern typically suggests severe right ventricular strain or hypertrophy, often seen in conditions like massive pulmonary embolism, severe pulmonary hypertension, or certain congenital heart defects. Some key points to consider when evaluating northwest axis deviation include:
- The clinical significance of this finding, as it is associated with a high incidence of significant congenital heart disease (CHD) in infants, with nearly half of the infants with northwest axis deviation found to have significant CHD 1
- The importance of clinical correlation with the patient's symptoms and medical history, as well as additional diagnostic testing such as echocardiography, chest imaging, or pulmonary angiography depending on the suspected underlying cause
- The urgency of intervention, which depends on the patient's clinical status, with immediate action needed for conditions like acute pulmonary embolism
- The fact that northwest axis deviation represents a significant departure from normal cardiac electrical patterns and should never be dismissed as a normal variant It is also worth noting that while other studies have discussed the importance of ECG interpretation in diagnosing and managing cardiac conditions, such as acute coronary syndromes 2 and the clinical significance of the QRS axis 3, the most recent and relevant study on northwest axis deviation is the 2025 study published in Cardiology in the young 1.