How safe are artificial heart valves?

Quite safe: In this day in age, several hundred thousand of these procedures have been performed successfully. Three types of valves: animal (porcine or bovine), bioprosthetic, mechanical. The latter requires long term blood thinners and blood test have to be performed periodically to ensure the blood is thinned enough. The latter tends to have a longer life, too.

Analyse risk/benefit: Artificial heart valves came on the medical scene in 1961. Prior to these life savers, open heart surgeons could repair damaged heart valves. A valve repair might last 1 to 6 years. The question you need answered is... Without a heart valve how will my health be? From that point you can get the risk of implanting and maintaining your new valve. Take a friend/family with you to help decide.