I have a PM/ICD combo and haven't taken any blood thinners, but my father in law has a pm/icd also and takes Coumadin. I know when he's on it, he has to be extremely careful with not getting scrapes or cuts and calling the dr if certain symptoms happen [can't remember specifics atm, but i'll ask].
Def discuss all options with your dr's.
I have a pacer and I am on coumadin because I also have AFib. If I did not, I would not be on coumadin.
I don't have the numbers for a Pacemaker, in fact I didn't know they require clot formation mitigation. Are you sure they do? Discuss with your Cardiologist. He/she can also give you any risk factors/numbers.
My recollection is that permanent atrial fibrillation if untreated with a blood thinner increases the risk of a stroke by slightly lower numbers, around 2-3% annual chance, cumulative I believe. That is roughly a 20-30% risk in 10 years. Again I do not propose this applies to a pacemaker, but give as a related reference. I do take warfarin, but I do not have any unusual bleeding risks.