If you are really concerned look into a Kardia device and check your heart frequently. Then maybe learn the 5-6-7 style of meditation. Inhale to the count of 5, hold that breath to the count of 6, then exhale to the count of 7. I'm not sure it will help in your particular case, but I also don't think it will do any further damage.

BTW...Mayo clinic has finally stated that Afib is not so dangerous to your heart as once thought, but PVCs are seriously wrecking the hearts of those who suffer with them. They cause heart failures due to the need to pump out large amounts of blood after the quick beats that fail to pump enough blood. The heart has then to send out a double amount in the follow up from the PVC. AND it makes the sufferer do a similar thing as if they had a heart attack...profuse sweating, shortness of breath, severe fatigue...all signs of a heart attack, but no heart attack.