I have PAC's . . .Same thing, but the Atrial valve contracts early. Take Beta blockers as well and avoid caffeine . . .
Related to the topic, i was having dizzy spells a few years back. I went for the full set of tests, including the Stress test. As I recall, it wasn't too bad . . . That said, i can't image doing that after a mild heart attack or being a heavy smoker . . .
I also had the Tilt Table Stress test. They gave me adrenaline to take my heart rate up to 140 beats per minute, strapped me to a table and put it in various positions. I didn't pass out (which I guess is the point of the test), but it certainly was one of the more unpleasant experiences of my life.