left axis deviation

ECG axis < -30 Etiology: 1) left anterior fasicular block (most common) a) left ventricular hypertrophy b) coronary artery disease c) idiopathic conduction system 2) myocardial infarction (inferior wall) 3) accessory pathway (WPW, posteroseptal location) 4) COPD 5) pulmonary embolism

References

Practical ECG Interpretation, T Evans, Ring Mountain Press, 1998