Left axis deviation can be associated with which conditions?

• A. Left ventricular hypertrophy and hypertension
• B. Right ventricular hypertrophy
• C. Pulmonary embolism
• D. Hyperkalemia

Answer: (A)

Left axis deviation shows a leftward shift of the overall ventricular depolarization vector on the frontal plane. This often happens when the left ventricle becomes dominant or mass increases, as with left ventricular hypertrophy due to chronic hypertension. The greater left-sided electrical force pulls the QRS axis toward the left, so the ECG reflects left axis deviation in this scenario. In contrast, right ventricular hypertrophy tends to move the axis to the right, pulmonary embolism with acute strain can produce right-axis deviation, and hyperkalemia mainly changes conduction and QRS morphology rather than causing a characteristic leftward axis shift.