Hi CTYankee,
Heart attacks (MI) damages heart muscle, and the heart's ability to adequately pump due to a loss of contraction functionality causing heart failure. Heart failure is an EF below 29% and normal is 55 to 75%. Your EF is 52% and there appears to be very little damage, if any, to the heart muscle. Three years ago my EF was below 29% due to a silent heart attack, and I was hospitalized with congested heart failure. With medication and doing everything right, my EF is 55%.
The statistics you cite may be true, but the statistics include many parameters, other conditions and situations i.e., heredity, lifestyle, diet, stressful occupation, lack of exercise, etc. Many people don't make any changes under their control, stop their medication, etc. There isn't much one can do about the heredity factor, but changes one can control will probably give a normal life span.