Final answer:
Patients with prosthetic cardiac valves require prophylactic antibiotics prior to dental procedures to prevent prosthetic-valve endocarditis.
Step-by-step explanation:
The question is about which patients require prophylactic antibiotics prior to dental procedures that could cause bacteremia, potentially leading to an infection such as bacterial endocarditis. The correct answer for which patients need prophylactic antibiotics is those with Prosthetic cardiac valves. Patients with prosthetic cardiac valves are at risk of developing prosthetic-valve endocarditis, which is a serious infection that can occur when bacteria enter the bloodstream during dental procedures and adhere to the abnormal valve surface. The American Heart Association recommends that these patients receive prophylactic antibiotics to prevent such infections.