I just want to thank you DnvrFox for this thread and for all those who have contributed to it. Sorry to resurrect it if it was put to bed, but it is a great source of comfort for other cyclists going through these terrifying experiences alone. It helps to know that these occurrences have been not uncommon in our athletic community and others.

Like Lady Hawk mine has involved strange bouts where my HR has suddenly shot up to 235 bpm+ during exercise. And once, while at work...where, feeeling decidedly not good, a sudden spike to 210+ led to a trip to the ER to find out what in tarnation was going on with me.

It was a quite an experience to find myself overnight in the ER with so many folk whose defibs had gone off or who were in one kind of cardiac distress or another. What a great group of folk, despite their troubles.

Anyway, for now I am on Metoprolol ER together with a less potent version of my normal BP Rx, Diovan HCT. Trying to figure out the next step with my Doctor and Cardiologist. Haven't ridden a bike --at least not hard -- in a few weeks -- part schedule/part fear of it happening again. Just some medium weight lifting and easy treadmill walk/run routines so far.