In acute infective endocarditis on native valves, which valve is most commonly affected?

In acute infective endocarditis on native valves, which valve is most commonly affected?

• A. Aortic
• B. Mitral
• C. Tricuspid
• D. Pulmonary

Answer: (B)

In native-valve infective endocarditis, left-sided valves are affected far more often than right-sided, with the mitral valve being the most commonly involved. This predominance is due to the mitral valve bearing high left-sided pressures and flow that can cause endothelial injury, creating a prime site for bacteria circulating in the blood to adhere and form vegetations, especially when virulent organisms such as Staphylococcus aureus invade quickly in acute cases. Preexisting damage from rheumatic disease, degenerative changes, or simple high-flow states further predispose the mitral valve to infection. In contrast, the tricuspid valve is more commonly hit in intravenous drug users because bacteria are introduced directly into the venous system and reach the right heart first, whereas the pulmonary valve remains rarely involved. So the mitral valve stands out as the most frequent target in acute infective endocarditis on native valves.

In native-valve infective endocarditis, left-sided valves are affected far more often than right-sided, with the mitral valve being the most commonly involved. This predominance is due to the mitral valve bearing high left-sided pressures and flow that can cause endothelial injury, creating a prime site for bacteria circulating in the blood to adhere and form vegetations, especially when virulent organisms such as Staphylococcus aureus invade quickly in acute cases. Preexisting damage from rheumatic disease, degenerative changes, or simple high-flow states further predispose the mitral valve to infection.

In contrast, the tricuspid valve is more commonly hit in intravenous drug users because bacteria are introduced directly into the venous system and reach the right heart first, whereas the pulmonary valve remains rarely involved. So the mitral valve stands out as the most frequent target in acute infective endocarditis on native valves.