What is the safest blood thinner for afib and how likely are the most serious side effects?

NOAC ( new anticoagulants) are safer than warfarin) apixaban appears to cause less bleeding in older people.

This depends on exactly why you need them. I would invest $20 and read uptodate.com for one week and then discuss with your team. Then you all should do what is called a risk benefit analysis and hey you can make the decision if you want to take it or stop it or what. Discuss.