INFECTIVE ENDOCARDITIS


I. Definitions, pathophysiology, and epidemiology

  1. An infection of the endocardium, including that which lines the heart valves
  2. Males affected more than females
  3. Most cases occur in patients with existing heart disease, particularly valvular abnormalities or artificial valves; also common in injection drug users
  4. Microbiology
    1. Gram-positive cocci are the most common bacterial agents (Streptococcus viridans is most common in pts with congenital heart disease; Staphylococcus aureus is the most common for pts with prosthetic heart valves or injection idrug users)
    2. Can also see HACEK group (a set of gram-negative organisms including Haemophilus spp., Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens and Kingella kingae).
  5. Prosthetic valve endocarditis
    1. Accounts for 7-25% of endocarditis in developed countries
    2. Risk is greatest in first 3mos after surgery and decrease after 6mos post-op
    3. Similar risk for mechanical and bioprosthetic valves, though early (first 60d) endocarditis more common in former and late (after > 1y) in the latter
    4. Early endocarditis usually coag-negative Staphylococci, Staph aureus, Strep, gream-negative aerobes, fungal, or diphtheroids
    5. Late cases usually coag-negative Staphylococci or Staph aureus
II. Clinical Presentation and diagnosis
  1. Clinical presentation is variable
  2. Symptoms often indolent and nonspecific (anorexia, weight loss)
  3. Fever is almost always present
  4. New hear murmur and heart failure may occur
  5. Systemic emboli can occur, causing any or all of the following-Less common in prosthetic valve 
    1. Neurologic deficits
    2. Petechiae
    3. Splinter hemorrhages
    4. Janeway lesions (small erythematous macules on palms and soles)
    5. Osler’s nodes (painful, red, raised lesions on hands/feet)
    6. Roth spots (retinal hemorrhages with white or pale centers)
  6. Sepsis and septic shock may occur
  7. Diagnosis generally confirmed by blood cultures though echocardiogram may show heart valve "vegetations" (transesophageal is more sensitive)

III. Prophylaxis--Guidelines per AHA 2007 (http://circ.ahajournals.org/cgi/reprint/CIRCULATIONAHA.106.183095)

  1. Note that these guidelines update prior, much more aggressive guidelines.  Update was based on review of evidence and finding that many of the assumptions on which the older guidelines were based are probably invalid (like that bacteremia from dental procedures is qualitatively more severe than bacteremia from everyday activities like toothbrushing).
  2. As of 2007 there are no publiched randomized placebo-controlled studies to evaluate efficacy of abx for prophylaxis of endocarditis prior to dental, GI, or GU procedures
  3. Endocarditis prophylaxis "may be reasonable...although its effectiveness is unknown" for patients with any of the risk factors for severe complications of endocarditis listed below, for the following procedures:
    1. Dental procedures in which the gingiva or periapical region of a tooth are manipulated, or in which the oral mucosa is perforated (Class IIb recommendation)
    2. Invasive procedure of respiratory tract that involves incision or biopsy of respiratory mucosa (Class IIb recommendation)
    3. NO prophylaxis recommended for GI or GU procedures, EXCEPT:
      1. Elective urinary tract manipulation in presence of a known enterococcal urinary tract infection or colonization (in that case, "may be reasonable" to treat to eradicate enterococci from the urine; Class IIb recommendation)
      2. Non-elective urinary tract manipulation in presence of a known enterococcalurinary tract infection or colonization (in that case, pre-treat with a med effective against enterococci; Class IIb recommendation e.g. amoxicillin, ampicillin, or vancomycin).
  4. Risk factors for severe complications of endocarditis, for which endocarditis prophylaxis may be appropriate:
    1. Prosthetic Cardiac Valve
    2. History of prior infective endocartitis
    3. History of cardiac transplantation with subsequent cardiac valvulopathy
    4. Congential Heart Disease AND
      1. No h/o repair (or repair consisting only of palliative shunts and conduits)
      2. History of complete repair in prior 6mos
      3. History of repair but residual defects at or adjacent to the site of a prosthetic patch or device
  5. Antibiotic regimens:
    1. Timing
      1. Single dose 30-60min before the procedure; may be administered up to 2h after procedure if inadvertently omitted
    2. Drugs
      1. Amoxicillin 2g (or, if child, 50mg/kg) PO is first-line
      2. If unable to take oral meds:
        1. Ampicillin 2g (or, if child, 50mg/kg) IM/IV, OR
        2. Cefaxolin or Ceftriaxone 1g (or, if child, 50mg/kg) IM/IV
      3. If allergic to penicillins or ampicillin:
        1. Cephalexin 2g (or, if child, 50mg/kg) PO, OR
        2. Clindamycin 600mg (or, if child, 20mg/kg) PO, OR
        3. Azithromycin or Clarithromycin 500mg (or, if child, 15mg/kg) PO
      4. If allergic to penicillins or ampicillin AND unable to take oral meds:
        1. Cefazolin or ceftriaxone 1g (or, if child, 50mg/kg) IM/IV (don't use if h/o anaphylaxis, angioedema, or urticaria w/penicillins), OR
        2. Clindamycin 600mg (or, if child, 20mg/kg) IM/IV

IV. Diagnosis

  1. Clinical symptoms (primarily constitutional; sometimes secondary to cardioemboli)
  2. Blood cultures
  3. Transesophageal echocardiography
  4. Multislice chest CT w/contrast
    1. May be similar in sensitivity to TEE and may pick up certain lesions not seen on TEE (but also vice-versa, e.g. TEE may pick up flow abnormalities from mitral valve perforations (J. Am. Coll. Cardiol. 53:436, 2009-JW)

V. Management

  1. Typically treated with antibiotics x 4-6wks, initially empirically with vancomycin + gentamicin (after obtaining 2 sets of blood cultures) but then guided by culture results
  2. Anticoagulation is sometimes used in patients with prosthetic valve endocarditis given high incidence of systemic embolization (40%)
  3. Surgery may be necessary to replace an infected valve-Potential indications include:
    1. Vegetation, specifically:
      1. Persistent vegetation after systemic embolization
      2. Vegetation on anterior leaflet of mitral valve, particularly if >10 mm
      3. >1 embolic event during first 2 weeks of antimicrobial therapy
      4. Increase in vegetation size despite appropriate antimicrobial therapy
    2. Valvular dysfunction, specifically:
      1. Acute aortic or mitral insufficiency with signs of ventricular failure
      2. Valve perforation or rupture
    3. Perivalvular extension, specifically:
      1. Valvular dehiscence, rupture or fistula
      2. New heart block
      3. Large abscess or extension of abscess despite appropriate antimicrobial therapy
  4. In a retrospective study in 252 pts with infectious endocarditis (none were IV drug users), those who underwent early surgery (replacement of infected valve before completion of 4-6wks of antibiotics) vs. those who did not, mortality over 8y f/u was sig. lower in the former (40% vs. 65%) (Clin. Inf. Dis. 33:1636, 2001--AFP)
(Sources include Core Content Review of Family Medicine, 2012)