Infective Endocarditis — Clinical Case

DCE Long Case

Patient brief (provided to trainee)

Patient: Mr William Thompson, an older man. ^[1]

Presenting complaint: Days of fever, drenching night sweats, fatigue, and progressive exertional dyspnoea — now breathless on minimal exertion. Recently, a transient episode of left arm weakness and slurred speech that resolved completely over hours. ^[1]

Past history:

• Rheumatic fever age 12, leading to chronic mitral regurgitation
• Mechanical mitral valve replacement (St Jude) 6 years ago for severe symptomatic mitral regurgitation
• Atrial fibrillation (paroxysmal, now likely persistent)
• Hypertension
• Gout
• No known drug allergies ^[1]

Current medications:

• Warfarin 6 mg daily (INR target 2.5-3.5)
• Frusemide 40 mg daily
• Perindopril 5 mg daily
• Allopurinol daily ^[1]

Social history: Retired dairy farmer, lives with wife, ex-smoker, drinks alcohol daily in moderation. No illicit drug use. Recent hospitalisation 3 weeks ago for cellulitis of the right leg treated with oral flucloxacillin. ^[2]

Examination findings (trainee elicits):

• Conscious, alert, diaphoretic, tachypnoeic at rest, sitting upright at 45 degrees
• Temperature 38.6 degrees Celsius, blood pressure 110/65, heart rate 96 irregularly irregular, respiratory rate 22, oxygen saturation 92% on room air
• Hands: several splinter haemorrhages in nail beds; a painful, tender, pea-sized nodule on the pad of the right index finger (Osler node); two painless erythematous macules on the right palm (Janeway lesions)
• Eyes: conjunctival petechiae; no Roth spots on fundoscopy
• Cardiovascular: irregularly irregular pulse, JVP elevated 4 cm, loud prosthetic click with a new grade 3 pansystolic murmur at the apex radiating to the axilla, soft S3, no parasternal heave
• Respiratory: bibasal fine inspiratory crackles to mid-zones
• Abdomen: splenomegaly 3 cm below the costal margin, non-tender, no pulsatile liver
• Neurological: no residual deficit from the TIA, no focal signs
• No peripheral oedema ^[1]

Investigations:

• FBE: Hb 108, WCC 14.2 (neutrophilia), platelets 280, ESR 85, CRP 145
• U&E: creatinine 145 (baseline 90), eGFR 42, normal electrolytes
• LFTs: mildly elevated ALP, normal bilirubin and ALT
• INR 2.8
• Blood cultures: Staphylococcus aureus in 3 of 3 sets, methicillin-sensitive
• ECG: atrial fibrillation, HR 96, normal PR interval, normal QRS, no ischaemic changes
• Chest X-ray: pulmonary venous congestion, small bilateral pleural effusions, normal cardiac silhouette
• Transthoracic echo: 10 mm mobile vegetation on the prosthetic mitral valve, new paravalvular regurgitation with jets, LVEF 55%, moderate pulmonary hypertension (RVSP 45 mmHg)
• CT head (after TIA): small right parietal infarct, no haemorrhage ^[1]

Candidate's structured presentation (model)

Opening statement: ^[1]

"Mr Thompson is an older retired dairy farmer who presents with days of fever, night sweats, and progressive dyspnoea, complicated by a recent transient ischaemic attack. He has a mechanical mitral valve replacement from 6 years ago and is on warfarin. On examination he is febrile, hypoxic, with signs of heart failure, a new paravalvular murmur, and the peripheral stigmata of infective endocarditis — Osler nodes and Janeway lesions. Blood cultures have grown methicillin-sensitive Staphylococcus aureus and echo shows a vegetation on his prosthetic mitral valve with new paravalvular regurgitation. ^[3]

His main problems are:

1. Definite prosthetic valve infective endocarditis due to methicillin-sensitive Staphylococcus aureus
2. Heart failure from new paravalvular regurgitation — the strongest surgical indication
3. Recent transient ischaemic attack with a small right parietal infarct on CT — an embolic neurological complication affecting surgical timing
4. Acute kidney injury — multifactorial
5. Anticoagulation management of his mechanical valve during acute IE and surgery
6. Portal of entry — recent cellulitis and hospitalisation suggest healthcare-associated Staphylococcus aureus bacteraemia
7. Atrial fibrillation with a rapid rate — rate control needed" ^[1]

Investigation summary: ^[1]

"His transthoracic echo confirms a mobile vegetation on the prosthetic mitral valve with new paravalvular regurgitation, which is the source of his heart failure. I would obtain urgent transoesophageal echocardiography, which is mandatory in all prosthetic valve IE to define paravalvular abscess, dehiscence, and the mechanism of regurgitation. His CT head shows a small right parietal infarct from his embolic event, with no haemorrhage — this influences surgical timing. His blood cultures confirm MSSA. His AKI with raised creatinine is multifactorial — sepsis, heart failure, and possible antibiotic nephrotoxicity from his recent flucloxacillin course." ^[2]

Management plan: ^[2]

1. Immediate heart failure management:

   • Sit upright, high-flow oxygen, IV frusemide 40 mg (may need higher doses given his background diuretic use)
   • Rate control for atrial fibrillation if the rate remains rapid — consider digoxin or amiodarone (avoid beta-blockers acutely given hypotension) ^[1]

2. Antibiotic therapy:

   • Flucloxacillin 2 g IV 4-hourly (12 g/day) for at least 6 weeks — MSSA prosthetic valve IE
   • Add rifampicin 300 mg IV/PO 12-hourly once bacteraemia has cleared (typically after 3-5 days of negative cultures) — essential for sterilising the biofilm on prosthetic material
   • Withhold gentamicin initially given his AKI — reassess if bacteraemia does not clear by day 5-7 ^[2]

3. Urgent TOE and surgical referral:

   • Urgent transoesophageal echo to define the paravalvular anatomy
   • Immediate Endocarditis Team referral — cardiology, infectious diseases, cardiac surgery
   • Surgical indication: heart failure from paravalvular regurgitation (strongest indication) plus prosthetic valve Staph aureus IE plus recent embolic event
   • Surgical timing: he has a small ischaemic infarct on CT (not haemorrhagic) — ideal deferral is 2-4 weeks, but if heart failure is refractory, early surgery may proceed after neurosurgical consultation ^[4]

4. Anticoagulation management:

   • Stop warfarin, convert to unfractionated heparin infusion (short half-life, reversible)
   • Monitor INR to below 1.5 before surgery
   • Anticipate marked warfarin-rifampicin interaction postoperatively (rifampicin will increase warfarin dose requirement approximately two- to three-fold)
   • Do NOT switch to DOAC — mechanical valve contraindicates DOAC ^[1]

5. Neurological surveillance:

   • Repeat CT head if any new neurological symptoms
   • CT angiography of cerebral vessels if mycotic aneurysm suspected (low threshold in this patient given his embolic event)
   • Neurosurgery and interventional neuroradiology involvement if aneurysm found ^[2]

6. Source identification:

   • Recent cellulitis and hospitalisation 3 weeks ago — healthcare-associated Staphylococcus aureus bacteraemia likely from IV cannula or skin entry
   • Dental review to exclude oral source
   • Remove any indwelling lines ^[1]

7. Long-term:

   • 6 weeks minimum IV antibiotics (flucloxacillin plus rifampicin) — likely via PICC line and OPAT once stable
   • Post-treatment echocardiographic surveillance
   • Lifelong IE prophylaxis (high-risk: prosthetic valve and prior IE)
   • Education on recurrence symptoms and dental hygiene ^[1]

Examiner discussion questions

Q: "This patient has a small ischaemic infarct on CT. How does this change your surgical timing?" ^[2]

"An ischaemic embolic stroke in IE complicates surgical timing because cardiopulmonary bypass requires systemic heparinisation, which risks haemorrhagic transformation of the infarct. The general rule is to defer valve surgery by at least 2 to 4 weeks after an ischaemic stroke, and approximately 4 weeks after a haemorrhagic stroke. However, this is balanced against the cardiac indication — if heart failure is refractory and life-threatening, the mortality of deferring surgery exceeds the neurological risk, and early surgery may proceed after neurosurgical consultation. The Endocarditis Team makes this decision jointly. For this patient, his infarct is small and his TIA has resolved, so I would aim for surgery within the next 1 to 2 weeks if his heart failure can be managed medically — but if he deteriorates, I would proceed sooner." ^[4]

Q: "What would you do differently if his CT head showed haemorrhage?" ^[1]

"Intracranial haemorrhage in IE may be haemorrhagic transformation of an embolic infarct, or rupture of a mycotic aneurysm. If there is haemorrhage, valve surgery is deferred approximately 4 weeks because the risk of rebleeding under heparinisation is substantial. I would order a CT angiogram of the cerebral vessels to look for a mycotic aneurysm, which would require neurosurgical or endovascular treatment before or instead of valve surgery. His anticoagulation would be stopped immediately and reversed. The Endocarditis Team would weigh the competing risks — but in general, haemorrhagic intracranial complications push surgery later than ischaemic ones." ^[2]

Q: "Why are you adding rifampicin, and why not from day one?" ^[2]

"Rifampicin is added to the regimen for prosthetic valve staphylococcal endocarditis because it penetrates the biofilm on prosthetic material and kills adherent bacteria that beta-lactams cannot reach. However, rifampicin must not be started until bacteraemia has cleared — usually 3 to 5 days after the first negative blood culture. If rifampicin is started while there is still high-inoculum bacteraemia, rapid emergence of rifampicin resistance occurs through selection of resistant mutants. This is a classic exam trap. The regimen for staphylococcal PVE is flucloxacillin (or vancomycin for MRSA) plus rifampicin (added after clearance) plus gentamicin for the first 2 weeks (where renal function permits). Total duration is at least 6 weeks." ^[3]

Q: "He develops acute severe left upper quadrant pain on day 5. What is the diagnosis and what do you do?" ^[1]

"Splenic infarction or splenic abscess from septic embolisation to the spleen is the most likely diagnosis. The left upper quadrant pain, often referred to the left shoulder (Kehr sign), is classic. I would examine for peritonism and splinting, and order a contrast CT of the abdomen. Splenic infarction is managed with analgesia and continued antibiotics. Splenic abscess — suggested by a gas-containing or rim-enhancing lesion — may require percutaneous drainage or splenectomy. Splenic abscess in IE is an indication for splenectomy, often performed at the time of valve surgery. Vaccination against encapsulated organisms (pneumococcus, meningococcus, Haemophilus influenzae type b) is given ideally at least 2 weeks before elective splenectomy, or after the operation when surgery is urgent." ^[2]

Q: "What is the evidence for early surgery in infective endocarditis?" ^[4]

"The key randomised trial is Kang et al, which randomised left-sided IE with severe valve disease and large vegetations to early surgery (37 patients, all operated within 48 hours) versus conventional treatment (39 patients). Early surgery cut the composite of in-hospital death and embolic events within 6 weeks (3% vs 23%; HR 0.10, 95% CI 0.01 to 0.82) with no 6-month mortality difference.^[4] The benefit was primarily from reduction in systemic embolism. However, this trial excluded patients with embolic stroke, required severe valve disease, and was a single-centre Korean study — so its generalisability is debated. The ESC guideline supports early surgery for large mobile vegetations with embolic risk, particularly when there is a prior embolic event, but emphasises the Endocarditis Team decision. Observational data from large registries (ICE-PCS) show that about half of left-sided IE patients undergo surgery, with benefit in those with heart failure, uncontrolled infection, and large vegetations." ^[4]

Q: "How would you counsel this patient and his family about prognosis?" ^[2]

"I would be honest but constructive. I would explain that prosthetic-valve S. aureus bacteraemia carries high mortality when definite, and that his heart failure, neurological event, and kidney injury are adverse prognostic features. I would explain the plan — surgery to replace or repair the infected valve, followed by 6 weeks of intravenous antibiotics — and that the team approach gives him the best chance. I would discuss the risks of surgery (operative mortality in the single digits to teens, risk of stroke, need for a new prosthetic valve) and the benefits (control of infection and heart failure). I would initiate advance care planning, ask about his values and preferences, and document a substitute decision-maker. I would emphasise that with prompt and coordinated care, many patients survive and return to a good quality of life." ^[3]