Leftward deviation of the electrical axis of the ECG means that the electrical axis of the QRS in the ECG is less than 30 degrees, which can be seen in some normal people and some patients with heart disease. Electrocardiogram (EKG) axis is the average direction of cardiac electrical activity, and is the angle between the maximum integrated vector in the frontal plane and the horizontal axis during depolarization and repolarization of the heart. The normal range of the EKG axis is from 30 degrees to 60 degrees, and the EKG axis is leftward biased when the QRS axis is less than 30 degrees. Some normal people may have mild leftward deviation of the EKG axis, therefore, if other cardiac related tests are not abnormal and there are no obvious symptoms, mild leftward deviation of the EKG axis is generally not considered as a pathological condition. Some patients with heart disease, such as left ventricular hypertrophy, myocardial infarction of the lower wall, and chronic cardiac insufficiency, may also have leftward deviation of the electrocardiogram.