Is a QRS (quasi-random signal) axis of -22 degrees indicative of left axis deviation?

QRS Axis of -22 Degrees and Left Axis Deviation

Yes, a QRS axis of -22 degrees is considered left axis deviation in adults, specifically moderate left axis deviation. 1

Definition and Classification of Left Axis Deviation

• In adults, the normal QRS axis is between +30° and +90° 1
• Left axis deviation is defined as a QRS axis less than +30° 1
• Moderate left axis deviation ranges from -30° to -45° 1, 2
• Marked left axis deviation ranges from -45° to -90° and is often associated with left anterior fascicular block 1, 2
• A QRS axis of -22° falls within the left axis deviation range (less than +30°) but does not reach the threshold for moderate left axis deviation (which starts at -30°) 1, 3

Clinical Significance of Left Axis Deviation

• Left axis deviation may be associated with various cardiac conditions but can also be a normal variant, especially with increasing age 2, 3
• The presence of left axis deviation alone has limited diagnostic value and should be interpreted in the context of other clinical and ECG findings 3, 4
• Common causes of left axis deviation include:
  • Normal aging process (natural leftward shift with age) 3, 5
  • Left ventricular hypertrophy 2, 3
  • Left anterior fascicular block (requires additional criteria beyond axis deviation) 1, 6
  • Cardiomyopathies 2
  • Congenital heart defects 1, 2

Diagnostic Approach for Left Axis Deviation

• For a QRS axis of -22°, consider the following approach:
  • Look for additional ECG abnormalities that might indicate underlying pathology 2, 3
  • Assess for other criteria of left anterior fascicular block (qR pattern in lead aVL, R-peak time in lead aVL ≥45 ms, QRS duration <120 ms) 1, 6
  • Consider the patient's age, as the axis naturally shifts leftward with increasing age 3, 5
  • Evaluate for clinical symptoms and risk factors for cardiovascular disease 2

Important Considerations

• Left axis deviation alone should not be considered synonymous with left anterior fascicular block, which requires additional criteria 6
• The correlation between the degree of left axis deviation and the presence of conduction abnormalities increases with more extreme leftward axis shifts 6, 7
• In a study of 8,000 Japanese-American men, more than 60% of individuals with left axis deviation had no other cardiovascular abnormalities 8

Common Pitfalls

• Overdiagnosis - treating left axis deviation as a primary diagnosis rather than a finding that requires clinical correlation 3
• Failing to consider age-related changes in QRS axis 3, 5
• Not distinguishing between isolated left axis deviation and left anterior fascicular block 6