pac

hi i have pac been caught on montor many times, but i have heard that the pac are the ones that causes a-fib is this true, i really have not ask my cardio guess i need to. but does anyone know if pac are the cause of afib or not.

[va_tony]

Yes, the PACs act as a trigger for the afib. They are not sufficient alone to cause afib.. ...you also need a willing atrium/substrate. I answered this question on this board recently but have been unable to find it.  Here is an answer I gave about 3 years ago on the Doctors' Heart Forum:

"To have afib, two conditions must be fulfilled: (1) you need an electrical trigger like the etopic pulse causing a PAC; and (2) you need an arrhythmic substrate (i.e., an atrium that is overly sensitive/susceptible either because of abnormal electrochemistry or size).

(1) Studies have shown (see e.g., http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15078396&dopt=Abstract ) that PACs almost always precede the start of afib (I read in another article where 93% of afib cases are associated with PAC initiation).

(2) The electrochemical susceptibilty/sensitivity of the substrate is related to factors such as stress, ingestion of alcohol, imbalance between critical ions (Na, Ca, Mg, K), etc. So a person with PACs would tend to be more susceptible to experiencing "holiday heart" even though their heart might otherwise be "structurally sound".

The other factor that makes the atrium highly susceptible is its size. The normal size range of the left atrium is 3-4 cm. Generally, atria enlarge as time passes (i.e., strong correlation with age, blood pressure, valve problems, etc.). So, if for no other reason, as a person ages their LA increases. AFIB is essentially an oscillation phenomena dependent on the surface area of the atria. Unfortunately relatively small changes in atrial size lead to faily large area differences. A person with an LA of say 4.5 cm has an atrial area that's 65% larger than someone with a LA of 3.5 cm (when the LA exceeds 5, the area more than doubles). So, even if that person's atrial electrochemistry is "normal", they are predisposed to support afib (i.e., the setup of multiple reeentrant electrical wavelets) if they have PACs. In such cases, to prevent afib, the sensitivity of the heart has to be turned way down using antiarrhythmic drugs or if ablation is opted, substrate modification is needed."

Because the ectopics that cause PACs normally originate in the pulmonary veins, the usual rf ablation to cure afib is a pulmonary vein isolation, which electrically isolates the pulmonary from the atria and prevents PACs.

Tony

[SillyHeart]

PACs do not CAUSE a-fib.  They trigger a-fib in a person already susceptible to a-fib.  So, it's not really something to worry about unless you have a history of it already.

[heartfluttersflyawayplz]

i do not have a history of it and have had palps /pac for 23 years but they seem to be worse and come 6-7 a min for weeks sometimes i have a really long one so was not sure if i need to start worrying about this .lol