Infective endocarditis in the elderly

Definition and burden. Infective endocarditis (IE) is infection of the endocardium, usually of the heart valves. In people over 65 the incidence is about four times that of the general population and mortality is about twice that of younger patients.

Predisposing factors. Undiagnosed degenerative (calcific) aortic valve disease and increased use of invasive procedures and implanted devices (pacemakers, prosthetic valves, intravascular catheters) are the main reasons for the rise. Other risks are diabetes and gastrointestinal and genitourinary tract cancers. Mitral annular calcification and mucoid mitral valve degeneration also predispose. In India, rheumatic valvular disease remains an important substrate.

Microbiology changes with age. The proportion due to Staphylococcus aureus falls with age, while enterococci and Streptococcus bovis (gallolyticus) emerge as major pathogens. Isolation of S. bovis mandates colonoscopy to look for colonic neoplasm. Viridans streptococci still predominate where rheumatic heart disease is common; coagulase-negative staphylococci cause device-related IE.

Atypical presentation. Fever may be absent or low grade. The older patient often presents with delirium, anorexia, weight loss, falls, fatigue or unexplained anaemia with a raised ESR/CRP. A new or changing murmur may be the only sign. Classical peripheral stigmata (Osler nodes, Janeway lesions, Roth spots, splinter haemorrhages) are uncommon, so diagnosis is frequently delayed.

Diagnosis. Take three sets of blood cultures from separate sites before antibiotics. Transthoracic echocardiography first; proceed to transoesophageal echocardiography if TTE is negative, or if there is a prosthetic valve or intracardiac device. Apply the modified Duke criteria. Send serology for culture-negative causes (Coxiella burnetii, Bartonella, Brucella).

Management. Prolonged intravenous bactericidal antibiotics for 4–6 weeks, guided by culture and sensitivity, with careful renal-adjusted aminoglycoside dosing. Surgery is indicated for heart failure, uncontrolled infection/abscess, prosthetic valve dehiscence, and large mobile vegetations with embolism — age alone is not a contraindication, though frailty raises operative risk. Antibiotic prophylaxis strategy should take age into account in global risk assessment before invasive gastrointestinal or genitourinary procedures.

2023 ESC Guidelines on Infective Endocarditis adopt the 2023 Duke–ISCVID criteria, which add cardiac CT angiography and 18F-FDG PET/CT as major imaging criteria (especially valuable for prosthetic valve and device infection in older adults). They also endorse partial oral step-down antibiotic therapy after at least 10 days of intravenous treatment in stabilised left-sided IE (POET trial), and outpatient parenteral antibiotic therapy — both reduce prolonged hospitalisation and deconditioning in frail elderly patients.