Has aorta & mitral regurgitation & afib. Dentist said come every 6 months. No dental problems since 1964. What do u think?

non-sequitur. Aortic and mitral regurgitation do not constitute an indication for dental care. That said, everyone should try to have routine dental care done twice a year, regurgitation or not.
Good advice. Better not to take chances. Things happen as one ages, both medically and dentally and routine dental care is important to both preventing dental problems and if any develop, treating them in the early stages rather than having them develop into more serious issues.