Left deviation of the electrical axis of the heart is the leftward deviation of the heart’s electrical axis. Leftward deviation of the electrical axis of the heart can be caused by age factor, body size factor, high blood pressure, heart disease and so on. 1. Age factor: Cardiac eccentricity is usually related to age factor. Usually, newborn babies tend to have right deviation of the cardiac electrical axis, while the elderly tend to have left deviation of the cardiac electrical axis. 2. Body type: According to relevant research findings, short and fat people are prone to left deviation of the cardiac electrical axis, and thin people may have right deviation of the cardiac electrical axis. 3. High blood pressure: High blood pressure can lead to thickening of the left ventricle, which can cause left deviation of the heart’s electrical axis. 4. Heart disease: Some heart diseases can also lead to left deviation of the heart’s electrical axis, such as coronary heart disease, cardiomyopathy, myocarditis and so on. It is recommended to go to the hospital in time to reduce the harm to the body.