I had a "cardiac adventure" in 2015. All is well now. I'm not any kind of medical professional, but here are the comments that come to mind.
Red flags went up for me when the doc said it looked like you were having a heart attack and then didn't order a basic follow on test to confirm. When I was in the hospital, they did a blood test for "troponin", which is supposed to make sure you didn't have a heart attack.
Are you getting a coronary calcium scan too? They aren't always covered by insurance, but are fast and cheap-- I had cut out an article years before about this test (the article said to get the test before you let your doc put you on statins..) and my cardiologist and I thought it was worth doing. Mine cost 75 bucks and lasted all of 5 minutes. You get a result back that is a number to tell you how blocked up your coronary arteries are. (Mine was 0, so I celebrated with chocolate fudge cake..)
I had an echocardiogram in the hospital and the basic treadmill stress test (Bruce protocall) at his office a week or so later. Some thoughts on the stress test specifically:
--Although I hadn't been running over the last several years, I was/am still fairly active. The techs at the stress test tried to caution me that all I needed to do was get to 80% of my predicted max heart rate. I had read that if you ran a lot in the past, your max HR wouldn't decrease as much as predicted. Despite them giving me several hints like "you're done now, you can stop", I went on to my actual max HR. IF I was going to blow a gasket, I wanted to do it in the doc's office and not out in the wilderness on a fishing or hiking trip. I got to 108% of their prediction. Not that it's a contest, but I wanted to know where I stood.
--They told me to wear exercise clothes when I booked the session. After running on the treadmill all wired up long enough to get to my max HR, it would have been a good idea to bring along a couple towels to dry off with a little.
--The test isn't over the second you get off the treadmill. My Dad had a stress EKG many years ago. He did fine on the hamster wheel, but after he got off, he started feeling light headed. His blood pressure totally crashed, and they made him lie down and got the doc in there. Apparently, your blood vessels can get less elastic as you age, so in his case, they opened up during the exercise part (they gradually increase the speed and incline). At the end of the test, they just stop the treadmill so there was no gradual reduction and hence the pressure drop. He'll be 90 in a few months so no harm done.
Good luck on your test. It's nice to know what's going on.