American Society of Addiction Medicine (ASAM) Assessment 2025 – 400 Free Practice Questions to Pass the Exam

Infective endocarditis in heroin users is most commonly associated with the tricuspid valve. This is mainly due to the method of injection that many heroin users employ, which often involves injecting into peripheral veins. When substances are injected into these veins, bacteria from the skin can enter the bloodstream and subsequently settle on heart valves.

The tricuspid valve is particularly vulnerable in this population because of its anatomical position and the direct blood flow from venous return. When the right side of the heart is affected, it reflects the typical pattern seen in intravenous drug users, as opposed to the left-sided heart valves, which are more frequently involved in endocarditis related to other risk factors such as underlying heart disease or conditions that disrupt the surface of those valves.

While the mitral, aortic, and pulmonic valves can be affected by infective endocarditis, in the context of heroin use, the tricuspid valve is the most likely to be involved due to the mechanisms of infection related to drug use practices.