10 points difference may be only intra-observation variation although usually we expect more consistency than that.Your heart attack sounds rate at your age and lack of risk factors but such does indeed occur. Now in your case you probably had some heart muscle cells that does but a group of heart muscle tar was injured or stunned but not irreversibly damaged.
The stunned myocardium theory fits very well with your history and results .
So as long as you do not have another event ( heart attack) then there is no reason now to expect further significant change in your echo results.
The emphasis is to control risk factors. Daily low dose aspirin, lower cholesterol, watch blood pressure. These would be the main factors for you!!
Your echo is fine and no reason to worry. It fits as I said with injury and stunned heart muscle that has normalized again in function
There is no need for frequent exmchocardiograms for you!!
Keep check periodically on your blood pressure.
I hope that this is helpful for you.Let me know if you have further questions or concerns.Best regards,
Anthony Bray MD