Cox’s Conference: Infective prosthetic valve endocarditis

At today’s Cox’s Conference, Dr. Elizabeth McGehee with expert discussant Dr. James Luby presented a case of infective prosthetic valve endocarditis. 

Case:

The patient was an 81 year old white woman with a history of critical aortic stenosis and moderate-to-severe mitral stenosis status post surgical mitral valve and aortic valve bioprosthetic replacements three years prior to admission, untreated hepatitis C without cirrhosis, and hypertension. She presented to her primary care physician with complaints of numerous neurological disturbances. Four months prior to admission, she had a syncopal episode and possible receptive aphasia characterized by difficulty reading and pronouncing words at church. She was seen at an outside hospital where she was noted to be hypertensive and had negative computed tomography of her head. Several months later, she noted a transient episode of blurred vision and weakness while watching television; a similar episode recurred a few weeks prior to admission. Her son also reported progressive short-term memory loss, confusion, and gait instability. Her internist ordered an MR brain which showed multiple embolic strokes involving her right cerebellum, left corona radiatia, periventricular white matter, and left basal ganglia. Upon further history, the patient was noted to have undergone several dental procedures with prophylactic amoxicillin prior to presentation.

Physical examination demonstrated a 3/6 systolic ejection murmur loudest at the right upper sternal border, several nailbed hemorrhages, and a small purpuric pinpoint nontender lesion on the pad of her left fourth finger concerning for a developing Janeway lesion.

She underwent transthoracic echocardiogram which showed no vegetation, well seated bioprosthetic valves with trace regurgitation, LVEF of 75%, a hyperdynamic left ventricle, and a collapsible IVC. Subsequent transesophageal echocardiogram revealed paravalvular vegetation adjacent to the mitral valve sewing ring, multiple, mobile frond-like vegetations extending onto the surface of the mitral valve prosthetic leaflet, and possible developing phlegmon. There was moderate perivalvular regurgitation. Blood cultures were positive for Staphylococcus warneri.

She initially was treated with vancomycin, gentamycin, and rifampin and narrowed to nafcillin upon return of sensitivities. Gentamycin was continued for 2 weeks for synergy and rifampin was continued for biofilm penetration in light of bioprosthetic valve endocarditis. During admission, she was transferred to the ICU for progressive 1st degree heart block with concern for progression of perivalvular abscess and ultimately surgical mitral valve and aortic valve replacement in setting of embolic phenomenon, vegetation size, and progressive heart block.

Conference Pearls:

  • Transthoracic echocardiography is insensitive for infective endocarditis (up to 75%). Transesophageal echocardiography should be obtained when TTE is negative and clinical suspicion is high
  • Acute PR prolongation is a sign of paravalvular abscess and poses risk of progressive, higher grade heart block. This requires urgent surgical consultation and ICU monitoring.
  • Indications for surgical treatment for native valve endocarditis:
    • valvular dysfunction leading to heart failure
    • paravalvular extension of infection with development of annular or aortic abscess
    • destructive lesion
    • heart block
    • difficult-to-treat pathogens: fungi, VRE, pseudomonas aeruginosa
    • persistent bacteremia or fever >7 days despite adequate antimicrobial therapy
    • recurrent embolic phenomenon
    • large and/or mobile vegetation unlikely to be cured with antimicrobial therapy alone or at high risk of embolism
  • Indications for surgical treatment of prosthetic valve endocarditis
    • heart failure from valve dehiscence, intracardiac fistula, or severe valve dysfunction
    • consequent heart block, annular or aortic abscess
    • difficult-to-treat pathogen
    • persistent bacteremia despite appropriate antibiotic therapy for 5 to 7 days
  • In 1965, Drs. Kilpatrick, Greenberg, and Sanford (Arch Intern Med. 1965;115(6):730-735. ) conducted a study at Parkland Memorial Hospital of 574 patients admitted to the hospital. 59 (10.3%) were found to have splinter hemorrhages. None of those patients were found to have bacterial endocarditis, demonstrating that splinter hemorrhages are a very non-specific exam finding for endocarditis
  • Risk factors for infective endocarditis:
    • intravenous drug use
    • poor dentition or recent dental manipulation
    • male gender, age >60
    • history of infective endocarditis
    • valvular heart disease
    • HIV
    • chronic hemodialysis
    • prosthetic heart valves
    • intravascular devices
    • bicuspid aortic valve, aortic stenosis, pulmonic stenosis, VSD, PDA, aortic coarctation, tetralogy of Fallot, rheumatic heart disease