I have rbbb for over 20 years they said I was born with it , I'm still very anxious about it , the worrying about it has ruined my life really , yet I'm still here 42 now and still it's winning , the Internet is crap when it comes to answering is it harmfully , don't think anybody knows :(
I have had an EKG and ECG a 24 hour Monitor and blood test, all came back normal exceot my good colesterol was a tad low, but nothing dieting cant fix. They didnt feel it necissary to do a stress test or anything because they didnt see anything on my 24 hour monitor.
After I was diagnosed with an RBBB two years ago I researched for the answer to your question and there are very few answers. Yes many people with it are born with it. I know I didn't have it 20 years ago at my last ECG. I also have episodic benign palpitations. Anxiety can make your palpitations worse. I know it is not very comforting to know that there is nothing to worry about when you are experiencing palpitations. Have you had a complete cardiac work up? echo and CTA scan? Just stay heart healthy, easier said than done.