A right axis deviation on an ECG is most likely caused by what condition?

The presence of right axis deviation on an ECG is likely linked to conditions related to increased right heart strain or altered conduction due to right-sided heart issues. A myocardial infarction, particularly one affecting the right ventricle or inferior wall of the heart, can lead to an imbalance in electrical conduction pathways in the heart. This can manifest as a right axis deviation on the ECG, indicating that the heart's electrical activity is directed more toward the right side.

While left ventricular hypertrophy and ischemia can affect the axis of the heart's electrical activity, they are typically associated with leftward shifts or can cause other complications that may not specifically result in right axis deviation. On the other hand, right axis deviation is often a clear indicator of issues such as right ventricular hypertrophy, pulmonary conditions, or other right-sided heart complications, affirming that myocardial infarction particularly can instigate such deviations by impacting blood flow and electrical conduction in ways that shift the axis to the right.