I've heard of it called that also. It really depends on your life style.
Stress, smoker, drinker, work a holic, not enough sleep, google will give more info. than I can right now.
I had issue a while ago, within the last five years to be exact.
I drank beer every night after work, casual, never a fallen' down type drunk.
One day 6 years ago, I woke up felt okay, bent down to put my shoes on and whamo' heart was beating twice as normal. I thought I was going to die right there w/my new born girl and wife was not home, nobody else around at all.
I regained my breathing, I was pail as a white sheet and weak.
Alcohol causes the heart to jump when more of it than blood are running through your veins. Weird but after the Dr. said stop drinking or you're going to die within 5 to 8 years or less, I stopped cold turkey and have been fine ever since.
It happend a few other times shortly after, my heart rate was 136 to 155 beats a minute. Bought a home monitor when Dr. said to do so.
I would never know when I was going to start feeling like crap, it was very spontianious and scary.
I don't re-call right now which word Dr. said type of re-lated problem was, but he mentioned what you have also.
I've never smoked or drank hard liquor. But a beer a day is okay, 3 or 4 isn't over twenty years for some people I guess.
I have a high metabolisim for starters. That didn't help much Dr. said.
I told the Dr. one day, I'm not ready to die yet, I have a car to restore, he said what about your family, oh yeah, them to, I was a little out of it, ha-ha.
Fluttering was what he described mine once.
I wish you well my friend.....
Mark