I think the thing is not to mark your records too vividly - it may come back to bite you!
A one-off near fainting experience could be caused by a very varied mass of reasons: Infection (low level), iron deficiency, and certainly migraine related issues can all cause that feeling. Nasty, but it just fades into history.
Checking your main hydraulic pump is of course important, but even in the wildest excursions from a regular beat, I've never felt faint, so the arrhythmia in itself might not be an issue. I emphasize might not.
There are other reasons to try to normalize that arrhythmia. I don't know if pacemakers are ever fitted for this alone. I now have several friends who have them. Walk in, local anesthetic, and walk out. Unbelievable compared to the early ones. They feel so much better afterwards.
If you've enjoyed good health for a long while, such an episode will seem alarming, but some people live their whole lives with fainting spells, and they carry on regardless. Clearly, they are not doing a demanding job.