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INFECTIVE ENDOCARDITIS
(IE)

GUIDELINES

• DEFINITIONS
• DIAGNOSIS
• IMAGING
• INDICATION AND TIMING OF SURGERY

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Endocarditis:

• Exudative and proliferative inflammatory alterations of the endocardium, characterized by vegetations on the endocardial surface or within the endocardium. 
• It may occur as a primary disorder (infective endocarditis) or as a complication of or in association with another disease (e.g., lupus erythematosus, rheumatic heart disease).

Infective Endocarditis: 

• Invasion and multiplication of microorganisms: 
  • On the endocardial surface.
  • Within the endocardium.
  • Within the myocardium
  • On prosthetic materials.
  • Within and around cardiac structures. 
• Includes conditions in which structures of the heart, most frequently the valves, harbour an infective process that lead to:
  • Valvular dysfunction.
  • Localized or generalized sepsis.
  • Sites for embolism.

Native Mitral Valve Endocarditis with Vegetation on Both Leaflets

Large Vegetation on a Bicuspid Aortic Valve 
(virtually occludes valve orifice)

​Tricuspid valve endocarditis

Infected Starr–Edwards Mechanical Prosthesis

Infected Aortic Valve Bioprosthesis

MODIFIED DUKE CRITERIA FOR THE DIAGNOSIS OF IE

MAJOR CRITERIA

Positive Blood Culture

Typical microorganisms for IE from two separate BC (in absence of primary focus) Strep. viridans Strep. bovis HACEK group Community Acquired Staph. aureus or enterococci

OR

Persistently positive BC (recovery of microorganism consistent with IE from: BC drawn more than 12 hours apart, or All  of three or majority of four or more separate BC, with first and last drawn  at least 1 hour apart

Evidence of Endocardial Involvement:

Positive Echocardiogram for IE: Oscillating intracardiac mass (in the absence of an alternative anatomic explanation) On valve of supporting structure. In path of a regurgitant jet. On implanted material.

OR

Abscess, or New partial dehiscence of prosthetic valve, or New valvular regurgitation.  * (increase /change in a preexisting murmur is not sufficient for diagnosis)

HACEK Group:

• Haemophilus
• Actinobacillus
• Cardiobacterium 
• Eikenella
• Kingella

MINOR CRITERIA

Predisposition: Predisposing Heart condition. IV drug use. Fever > 38C

Vascular Phenomena: Major arterial emboli. Septic pulmonary infarcts. Mycotic aneurysm. Intracranial haemorrhage. Conjunctival haemorrhage. Janeway lesions.

Immunologic Phenomena: Glomerulonephritis Osler nodes. Roth spots. Rheumatoid factor.

Microbiological Evidence: Positive BC (but not meeting major criteria), or Serologic evidence of active infection, with organism consistent with IE.

Echocardiography: Consistent with IE (but not meeting major criteria).

Definitive Diagnosis	Two Major Criteria  One Major + Three Minor Criteria Five Major Criteria
Possible Diagnosis	One Major + One Minor Criteria  ​Three Minor Criteria

Echocardiography:

• Echocardiography Is the imaging of choice for all cases with clinical suspicion of endocarditis.
• Echocardiogram should be repeated weekley if the first TOE study was not conclusive.

IE: Echocardiographic and Clinical Features Suggesting Potential Need for Surgery

Vegetations: Persistent vegetation after systemic embolization. AML vegetation (particularly > 10 mm in size). One or more embolic events  during first 2 weeks of antimicrobial therapy. Two or more embolic events during or after antimicrobial therapy. Increase in vegetation size after 4 weeks of antimicrobial therapy.

Valvular Dysfunction: Acute AR  or MR with signs of ventricular dilatation. Heart failure not responding  to medical treatment. Valve leaflet perforation or rupture.

Perivalvular Extension: Valvular dehiscence, rupture or fistula. New heart block. Large abscess or extension of abscess despite appropriate antimicrobial therapy.

TOE showing multiple vegetations on the Aortic valve

TTE showing large vegetation on posterior leaflet of MV (arrow)

TTE showing large (4 cm diameter) vegetation (VEG) on the tricuspid valve in an IV drug abuser

Apical 4-chamber view of TTE showing a large, mobile, lobulated vegetation (arrow) partially obstructing the tricuspid valve and prolapsing into the right ventricle

TOE showing vegetations on the MV

Complications of IE

Partial Detachment of a Mitral Prosthetic Annuloplasty Ring due to Suture Dehiscence.
(separation between the mitral annulus and the prosthetic ring).

IE of the AV showing severe AR and an aneurysm of the Sinus of Valsalva

TOE showing a fistula between the aorta and the left atrium
​in a patient with a mechanical aortic prosthesis

RCA Obstruction by an Embolized Vegetation from the AV Causing Total Occlusion

CT Scan Showing a Large Right Parietal Cerebral Abscess

IE: INDICATIONS FOR SURGERY

Congestive Heart Failure: CHF caused by: severe AR or MR valve obstruction ​by vegetations (rare). Severe acute AR or MR with echocardiographic signs of: elevated LVEDP or significant PHT. CHF secondary to prosthetic  valve dehiscence or obstruction

Periannular Extension: Most patients with abscess formation or fistulous tract formation

Systemic Embolism: Recurrent emboli despite appropriate antibiotic therapy. Large vegetations (>10 mm) after one or more clinical or silent embolic events after initiation of antibiotic therapy. Large vegetations and other predictors of a complicated course. Very large vegetations (>15 mm) without embolic complications, especially if valve-sparing surgery is likely (remains controversial).

Cerebrovascular Complications Silent neurologic complication or TIA and other surgical indications. Ischemic stroke and other surgical indications, provided that cerebral haemorrhage has been excluded and neurologic complications are not severe (e.g., coma).

Persistent Sepsis: Fever or positive blood cultures persisting more than 5 to 7 days despite appropriate antibiotic regimen, assuming that vegetations or other lesions requiring surgery persist and extracardiac sources of sepsis have been excluded. Relapsing IE especially when caused by organisms other than sensitive streptococci, or in patients with prosthetic valves.

Difficult Organisms: S aureus IE involving a prosthetic valve and most cases involving a left-sided native valve. IE caused by other aggressive organisms (Brucella, S. lugdunensis). IE caused by multi-resistant organisms (e.g., MRSA or vancomycin-resistant enterococci) and rare infections caused by gram-negative bacteria. Pseudomonas aeruginosa IE. Fungal IE. Q-fever IE and other indications for intervention.

​Prosthetic Valve Endocarditis: Virtually all cases of early PVE. Virtually all cases of PVE caused by S. aureus. Late PVE with heart failure caused by prosthetic dehiscence or obstruction, or other indications for surgery. Late PVE with periannular extension (abscess or fistulous tract) Late PVE with persistent bacteraemia, recurrent emboli, or relapsing infection while on appropriate antibiotics.

IE: ​TIMING OF SURGERY

Emergency Surgery (Within 24 Hours):​ NVE or PVE and severe CHF or cardiogenic shock caused by: Acute valvular regurgitation Severe prosthetic dysfunction (dehiscence or obstruction) Fistula into a cardiac chamber or the pericardial space

Urgent Surgery (Within Days): NVE or PVE with: persisting CHF signs of poor hemodynamic tolerance. signs of abscess. PVE caused by staphylococci or gram-negative organisms. Large vegetation (>10 mm) with an embolic event. Large vegetation (>10 mm) with other predictors of a complicated course. Very large vegetation (>15 mm), especially if conservative surgery is available. Large abscess and/or periannular involvement with uncontrolled infection.

Early Elective Surgery (During In-Hospital Stay): Severe AR or MR with CHF and good response to medical therapy. PVE with valvular dehiscence or CHF and good response to medical therapy. Presence of abscess or periannular extension. Persisting infection when extracardiac focus has been excluded Fungal or other infections resistant to medical care

SUMMARY 
​Indications and Timing 

INDICATION	TIMING	CLASS	LEVEL
Heart Failure Aortic or Mitral NVE or PVE with severe acute regurgitation or valve obstruction or fistula causing refractory pulmonary edema or cardiogenic shock	​Emergency	I	B
Aortic or mitral IE with: severe acute regurgitation, or valve obstruction and persisting heart failure, or echocardiographic signs of poor hemodynamic tolerance (early mitral closure or PHT	​Urgent	I	B
​Aortic or mitral IE or severe prosthetic dehiscence with severe regurgitation and no heart failure	​Elective	IIa	B
​Right heart failure secondary to severe tricuspid regurgitation with poor response to diuretic therapy	​Urgent/ elective	IIa	C
Uncontrolled Infection: ​Locally uncontrolled infection (abscess, false aneurysm, fistula, enlarging vegetation)	Urgent	I	B
​Persisting fever and positive blood cultures for more than 7 to 10 days and not related to an extracardiac cause	​Urgent	I	B
​Infection caused by fungi or multiresistant organisms	​Urgent/ elective	I	B
​PVE caused by staphylococci or gram negative bacteria (most cases of early PVE)	​Urgent/ elective	IIa	C
Prevention of Embolism: ​Aortic or mitral IE or PVE with large vegetations (>10 mm) following one or more embolic episodes despite appropriate antibiotic therapy	Urgent	I	B
​Aortic or mitral IE or PVE with large vegetations (>10 mm) and other predictors of complicated course (heart failure, persistent infection, abscess)	​Urgent	I	C
​Aortic or mitral or PVE with isolated very large vegetations (>15 mm)	​Urgent	Ib	C
​Persistent tricuspid valve vegetations >20 mm after recurrent PE	​Urgent/ elective	IIa	C