How does infective endocarditis manifest in the brain and what is its management?

Neurological Manifestations and Management of Infective Endocarditis

Infective endocarditis causes brain complications in 15-30% of patients through septic emboli, resulting in ischemic stroke, intracranial hemorrhage, mycotic aneurysms, brain abscess, and meningitis—all requiring immediate brain imaging (CT or MRI) and multidisciplinary management with specific timing algorithms for cardiac surgery based on the type of neurological event. 1

Clinical Manifestations

Ischemic Stroke and Embolic Events

• Ischemic stroke is the most common neurological complication, occurring in up to 40% of patients clinically, though MRI detects embolic lesions in 60-80% of IE cases 2
• Patients present with focal neurological deficits, though many strokes are clinically silent depending on the affected brain region 2
• Septic microemboli originate from infected cardiac vegetations and lodge at distal branching points in cerebral vessels 2
• Staphylococcus aureus infection carries the highest risk for neurological complications compared to other causative organisms 1

Intracranial Hemorrhage

• Hemorrhagic transformation can occur as intracerebral hemorrhage, subarachnoid hemorrhage, or subdural hemorrhage 2
• Hemorrhage may result from hemorrhagic transformation of ischemic infarcts or from ruptured mycotic aneurysms 3

Mycotic (Infectious) Aneurysms

• Occur in 2-4% of IE cases, though likely underestimated due to asymptomatic presentations 3, 1
• Result from septic arterial embolism to the vasa vasorum or intraluminal space with subsequent spread through intimal vessels 3
• These aneurysms are thin-walled and friable with high rupture tendency 3
• Unlike non-infectious aneurysms, size does NOT predict rupture risk 3
• Present with headache, confusion, seizures, or focal neurological deficits 3

Brain Abscess

• Presents with focal neurological deficits, headache, confusion, and seizures 2
• Can develop from septic emboli lodging in brain parenchyma 2

Other Manifestations

• Meningitis can occur, particularly if rupture into the meninges occurs 2
• Encephalopathy may develop from systemic infection or multiple microemboli 4

Diagnostic Approach

Immediate Imaging

• Perform immediate brain imaging (CT or MRI) for ALL patients with suspected neurological complications 1
• MRI with gadolinium contrast provides higher sensitivity than CT and may influence surgical timing decisions 1
• Exclude hemorrhagic transformation before proceeding with cardiac surgery 3

Vascular Imaging for Mycotic Aneurysms

• CT or MR angiography should be performed in any IE patient with neurological symptoms to detect intracranial infectious aneurysms 3, 1
• If non-invasive techniques are negative but suspicion remains high, conventional angiography remains the gold standard 3
• Vascular imaging is mandatory in patients with intracerebral hemorrhage to rule out ruptured mycotic aneurysm 1

Cardiac Imaging

• Perform transthoracic (TTE) and transesophageal echocardiography (TEE) to assess valve involvement and embolic risk 1

Management Algorithm

Multidisciplinary Team

• Establish immediate multidisciplinary team including infectious disease specialists, cardiologists, cardiothoracic surgeons, and neurologists 1

Antimicrobial Therapy

• Prompt initiation of appropriate antibiotics is crucial to prevent first or recurrent neurological complications 3, 1

Timing of Cardiac Surgery Based on Neurological Event Type

Silent Embolism or Transient Ischemic Attack

• Cardiac surgery should be performed WITHOUT DELAY if indicated (Class I recommendation) 3, 1

Ischemic Stroke

• Surgery should be considered without delay if there is heart failure, uncontrolled infection, abscess, or persistent high embolic risk, provided the patient is NOT in coma and cerebral hemorrhage has been excluded by CT or MRI (Class IIa recommendation) 3, 1
• This applies even to symptomatic ischemic strokes as long as there is no significant hemorrhagic transformation 1

Intracranial Hemorrhage

• Surgery should generally be postponed for ≥1 month (Class IIa recommendation) 3, 1
• In cases of small hemorrhages where cardiac surgery is urgent, earlier surgery may be considered based on individual risk-benefit assessment 1

Mycotic Aneurysms

• Ruptured aneurysms require immediate neurosurgical or endovascular treatment 3
• Very large, enlarging, or ruptured intracranial infectious aneurysms require neurosurgery or endovascular therapy (Class I recommendation) 3
• Unruptured aneurysms should be followed with serial cerebral imaging under antibiotic therapy 3
• If aneurysm size decreases or resolves, surgical intervention is usually unnecessary 3
• If aneurysm size increases or remains unchanged, intervention is likely required 3
• Voluminous and symptomatic infectious aneurysms require neurosurgery or endovascular therapy 3
• If early cardiac surgery is required with an unruptured aneurysm, preoperative endovascular intervention might be considered 3

Brain Abscess

• Cardiac surgery should NOT be delayed in patients with cerebral abscess 1
• In hemodynamically stable patients, consider draining the abscess first before cardiac surgery 5

Anticoagulation Management

Mechanical Valves with Embolic Stroke

• Discontinue anticoagulation for at least two weeks of antibiotic treatment to prevent hemorrhagic transformation 1

General Anticoagulation

• Heparin should be used cautiously in patients with IE 1
• In ischemic stroke associated with IE, there is no indication to start antithrombotic drugs 6
• In previously anticoagulated patients with ischemic stroke, replace oral anticoagulants with unfractionated heparin 6
• In intracranial hemorrhage, interrupt all anticoagulation 6

Prosthetic Valve Selection

• Bioprosthetic valves are preferred over mechanical valves in the context of embolic stroke to avoid the need for postoperative oral anticoagulation 1

Critical Contraindications to Immediate Surgery

• Coma 3
• Presence of cerebral hemorrhage (unless excluded by CT/MRI) 3
• Severe comorbidities 3
• Stroke with severe damage 3

Common Pitfalls

• Failing to obtain brain imaging in all IE patients with any neurological symptoms—this delays detection of mycotic aneurysms and hemorrhage 3
• Assuming aneurysm size predicts rupture risk—infectious aneurysms behave differently than congenital aneurysms 3
• Delaying cardiac surgery unnecessarily after ischemic stroke—most ischemic strokes do not require surgical delay if hemorrhage is excluded 3, 1
• Proceeding with cardiac surgery without excluding hemorrhagic transformation—this can lead to catastrophic outcomes 3
• Continuing anticoagulation after embolic stroke—this increases hemorrhagic transformation risk 1

Prognostic Considerations

• Neurological complications are associated with higher morbidity and mortality 1
• Cerebral embolic events pose an independent risk factor for mortality, even when subclinical 2
• Embolic risk is highest during the first 2 weeks of antibiotic therapy and relates to vegetation size and mobility 2