Update on Infective Endocarditis

Larry Baddour, MD

University of Tennessee

Pathogenesis

•Disruption of the endocardial layer as a complication of abnormal blood flow associated with underlying cardiac defect

•Bacterium-endothelium interaction with bacterial attachment and invasion of endothelial cells

Epidemiology

•Underlying valvular abnormality predisposing to infective endocarditis

–rheumatic fever

a common cause in the past

–mitral valve prolapse

currently represents the most common underlying cardiac abnormality

mitral valve prolapse

•risk for infective ednocarditis is 5x-8x

•mitral regurgitation increases the risk

•leaflet redundancy with myxomatous degeneration is a frequent finding

•age <20 , female predominate age >20 , male accounts for 60% age >50 , male accounts for 68%

Mitral Valve Prolapse

and Infective Endocarditis

Coagulase-negative Staphylococci

•can produce native-valve endocarditis in mitral valve prolapse

•usually subacute, difficult to diagnose, and disregarded as a contaminant

•delay in diagnosis and treatment may account for the severe complications

–myocardial abscess formation

–valvular insufficiency requiring valve surgery

–death

Prosthetic Heart Valve

•positive blood culture in hospitalized patients with underlying prosthetic valves can be a harbinger of endocarditis

•43% patients with nosocomial bacteremia or fungemia had prosthetic valve infection

•a serious complication

IV Drug Use

•Recurrent

•Polymicrobial

•Staph aureus accounts for the majority of cases of endocarditis

•tricuspid valve, either alone or in combination, us most often infected

Predisposing Factors

Polymicrobial Infective Endocarditis

Iv drug use

Central line

Prosthetic valve

Previous IE

Murmur

Dental procedure

Rheumatic disease

Miscellaneous

Polymicrobial Infective Endocarditis

clinical features

•IV drug use is the predominant risk factor

•younger age (mean 36.5 years)

•2/3 were male

•right-sided cardiac involvement in > 60%

•streptococci more frequent than S. aureus

•1/3 of patients died

•mortality rate is 4x higher for pure left- sides vs pure right-sided endocarditis