12 year-old MI, Still ticking

So I had an MI 12 years ago. I am 70 years old. I was late in detecting it. I received two stents. The physician told my wife I waited too long and that I would probably need a heart transplant some day. Today, 12 years later, I walk with my wife nearly every day, one to two miles. I mow my own yard, usually 1 to 2 hours, nonstop. We do weight training. I feel like a 12-year older version of myself. Basically, I feel good. I recently had an echocardiogram that suggested a 10 to 15% EF. So a followup treadmill stress test was completed. It suggested an EF of 38%. Now my cardiologist wants to repeat the echocardiogram, in addition to a 48-hour halter. I really don't want an ICD unless it is essential. Is the cardiologist grasping at straws.