I suffered from an irregular heartbeat, usually after training, which I confirmed with my heart rate monitor. I went to a cardiac specialist, he did an ECG, and I had a very characteristic trace that confirmed I had Wolff-Parkinson-White syndrome. In this, the heart has extra passageways to carry the beating impulse from one side of the heart to the other, and they shouldn't be there. What happens is the heart can short-circuit the normal control circuits, go into overload and stop.
This is curable with a surgical procedure that uses radio waves to zap the extra pathways in the heart, using probes they insert via the arteries and veins in the groin.
I had this treatment and I am now cured. However, it is bloody scary as they carry it out under local anaesthetic and you can see the electrodes on your heart via an x-ray screen as they do it, and they finish up with stopping your heart to ensure that they have zapped all the pathways. This lasted for 14 seconds for me and I guess it feels like you're having a heart attack. A side effect for me is that I am now much more susceptible to migraines and I have had to give up drinking coffee during the day.
If anyone out there suffers with this and want to talk about it, I'm more than willing to do so.
Euan, Melbourne, Victoria.