I know a cardiologist very well and his opinion of the ECG is that it is a good diagnostic tool for people over forty who have other cardiac indicators, chest pain etc. It is in his opinion of little use to predict any cardiac event and of some but not a lot of use to show previous damage. To get a full picture of how the heart is running you have to do a full cardiac workup and even then it can be wrong. There are many documented cases ( a few are pilots ) who passed extensive cardiac testing only to suffer a cardiac arrest shortly afterwards, likewise there are even more cases of people who showed something minor on an ECG and are still in the land of the living many years later. It is quite possible that you may not even have left axis deviation and what's showing up on the trace is an error generated in the machine because of your build or other factors.