Hi welcome to Healthcare Magic
The main cause for the left axis deviation is Hypertrophy(thickening) of the left ventricle,
that will lead to malfunction of the left ventricle,conduction defect in the left ventricle, all these will result in reduced cardiac out put... It is irreversible.. but you must stop the progression , by avoiding strenuous exercise, weight lifting, gym etc.. also reduce your LDL
level by decrease intake of cholesterol
rich foods, oily items...