Summary

Infective endocarditis (IE) is a microbial infection of the endocardial surface of the heart, predominantly affecting cardiac valves. Despite advances in diagnosis and treatment, IE remains life-threatening with in-hospital mortality of 15-30% and 1-year mortality approaching 40%. The epidemiology has shifted: previously dominated by rheumatic heart disease in young patients, IE now affects older patients with degenerative valves, those with prosthetic valves, and intravenous drug users. The Modified Duke Criteria remain the diagnostic cornerstone, combining microbiological evidence with echocardiographic findings. Early surgical consultation is essential, as up to 50% require valve surgery. Recognition requires high clinical suspicion, as presentations can be insidious and classical signs may be absent.

Key Facts

• Definition: Infection of endocardial surface with vegetation formation (platelets, fibrin, microorganisms, inflammatory cells)
• Incidence: 3-10 per 100,000 person-years; rising with aging population
• Mortality: In-hospital 15-30%; 1-year mortality 30-40%
• Morbidity: Embolic events 20-50%, heart failure 30-40%, perivalvular abscess 10-40%
• Peak Demographics: Bimodal - IVDU (20-40 years) and elderly degenerative (>65 years); Male:Female 2:1
• Pathognomonic Feature: Vegetation on echo with positive blood cultures for typical organisms
• Gold Standard Investigation: TEE - sensitivity 90-100% vs TTE 50-60%
• First-line Treatment: Empirical IV antibiotics + surgical evaluation
• Prognosis: With treatment 70% survive to 1 year; without surgery when indicated mortality exceeds 50%

Clinical Pearls

Diagnostic Pearl: Three blood culture sets from different venepuncture sites before antibiotics identify causative organism in >90%. Never give antibiotics before cultures in stable patients.

Examination Pearl: Splinter haemorrhages, Janeway lesions, and Osler nodes present in only 10-25%. New or changing murmur is the most important clinical sign.

Treatment Pearl: Prosthetic valve IE requires rifampicin to penetrate biofilm, but only after 3-5 days bactericidal therapy to prevent resistance.

Pitfall Warning: Negative cultures occur in 10-20% - consider prior antibiotics, fastidious organisms (HACEK, Coxiella, Bartonella), or fungal infection.

Mnemonic: FROM JANE - Fever, Roth spots, Osler nodes, Murmur (new), Janeway, Anaemia, Nail haemorrhages, Emboli

Why This Matters Clinically

Infective endocarditis is a great mimicker - missed or delayed diagnosis leads to catastrophic outcomes including stroke and death. Medico-legal cases frequently arise from failure to obtain blood cultures before antibiotics, inadequate echo assessment, and delayed surgical referral. Core topic for MRCP Part 2 and FRCS viva examinations. Healthcare-associated IE is increasing, making this relevant across all hospital specialties.

Structured Approach

General:

• Unwell, pale, febrile
• Cachexia, clubbing (late)
• Hands: splinter haemorrhages, Osler nodes
• Palms/soles: Janeway lesions

Cardiovascular:

• Pulse character, BP (wide in AR)
• JVP (RV failure)
• Apex displacement
• Auscultate for new/changed murmur
• Regurgitant murmurs: pansystolic (MR/TR), early diastolic (AR)

Peripheral:

• Eyes: Roth spots, conjunctival petechiae
• Mouth: palatal petechiae, dental caries
• Abdomen: splenomegaly
• Skin: petechiae, track marks
• Neuro: focal deficits

Special Tests

Natural History

Untreated IE is uniformly fatal. Pre-antibiotic mortality was 100%. Subacute may survive weeks-months untreated but invariably die from HF, emboli, or sepsis.

Outcomes with Treatment

Prognostic Factors

Good:

• Young age
• Right-sided IE (mortality 5-10%)
• Viridans strep or HACEK
• Early diagnosis
• Successful valve repair

Poor:

• Age >65
• Diabetes
• Prosthetic valve (mortality 30-50%)
• S. aureus (especially MRSA)
• Heart failure at presentation
• Major stroke
• Perivalvular abscess
• Delayed surgery

Key Guidelines

1. ESC Guidelines IE (2023) — Multimodal imaging, endocarditis team. Eur Heart J
2. AHA Statement (2015) — Antibiotic regimens, surgical timing. PMID: 26373316
3. BSAC Guidelines (2023) — UK-specific antibiotics. BSAC
4. NICE Prophylaxis (2016) — UK prophylaxis guidance. PMID: 27280619

Landmark Trials

POET Trial (2019) — Partial Oral Treatment

• n=400 stable left-sided IE
• Oral step-down vs continued IV
• Finding: Non-inferior with oral after 10 days IV
• Impact: Selected stable patients can switch oral
• PMID: 30152252

Early Surgery Trial (2012) — Kang et al

• n=76 with vegetation >10mm, high embolic risk
• Early surgery within 48h vs conventional
• Finding: Reduced embolic events 3% vs 23%
• Impact: Supports early surgery high-risk
• PMID: 22738096

ICE-PCS Registry (2009)

• n=2781, 25 countries
• Key finding: Surgery improves survival in appropriate candidates
• PMID: 19273776

Evidence Strength

What is Infective Endocarditis?

Infective endocarditis is a serious infection inside your heart. Bacteria from your bloodstream settle on heart valves and form a growth called a "vegetation". This damages the valve and can spread infection throughout your body.

Why does it matter?

Without treatment, it is fatal. Even with treatment it can cause:

• Heart failure
• Stroke
• Kidney damage
• Widespread infection

About 1 in 5 people do not survive, which is why quick diagnosis is essential.

How is it treated?

1. Antibiotics through a drip for 4-6 weeks
2. Heart surgery in about half of patients
3. Monitoring with blood tests and heart scans

What to expect

• Hospital 2-6 weeks typically
• Regular blood tests
• Repeat heart scans
• Some can finish antibiotics at home
• Full recovery takes months
• Long-term cardiology follow-up

When to seek help

Go to hospital if:

• Fever that won't go away with heart valve problem
• Sudden weakness on one side
• Breathlessness or chest pain
• If you inject drugs and have fever with breathing problems

Common Exam Questions

1. MRCP Part 2: "55-year-old with prosthetic aortic valve, 3 weeks fever. CoNS grown. What empirical antibiotics?"

2. PACES: "Examine the cardiovascular system. This patient has 3 weeks of fever."

3. FRCS Viva: "Indications for surgery in infective endocarditis?"

4. MRCP Part 1: "Which is a major Duke criterion?"

5. SCE: "IVDU with right-sided IE - which valve and imaging findings?"

Viva Points

Opening Statement:

"Infective endocarditis is microbial infection of the endocardial surface, typically affecting valves. Incidence 3-10 per 100,000, mortality 15-30%. Diagnosed using Modified Duke Criteria. 50% require surgery."

Key Facts:

• Duke: 2 major, or 1 major + 3 minor, or 5 minor
• Cultures positive 85-90% - three sets before antibiotics
• TEE sensitivity 90-100% vs TTE 50-60%
• S. aureus now commonest in developed countries
• Surgery for HF, uncontrolled infection, large vegetation + embolism

Evidence to Cite:

• "POET trial (2019, n=400) - oral step-down non-inferior"
• "ESC 2023 - early surgery within 48h for HF or very large vegetations"

Common Mistakes

• ❌ Antibiotics before cultures
• ❌ Not knowing Duke Criteria
• ❌ Missing TEE need for prosthetic valves
• ❌ Not knowing surgical indications
• ❌ Confusing Osler (painful) vs Janeway (painless)

Outdated:

• Routine dental prophylaxis - now high-risk only (UK)

Examiner Questions

1. "Cultures negative at 5 days?"

   • Extended incubation, serology for Coxiella/Bartonella, PCR

2. "Evidence for early surgery?"

   • Kang 2012: reduced emboli 3% vs 23%

3. "Patient develops stroke?"

   • CT head; if small ischaemic proceed; large haemorrhagic delay 2-4 weeks

Last Reviewed: 2026-01-01 | MedVellum Editorial Team

Medical Disclaimer: MedVellum content is for educational purposes. Clinical decisions should account for individual circumstances.