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• Specification of criteria for diagnosis of prosthetic valve endocarditis is fundamental
  oscar,m jolobe
  Published on: 11 June 2020

• Published on: 11 June 2020

  Specification of criteria for diagnosis of prosthetic valve endocarditis is fundamental

  • oscar,m jolobe, retired geriatrician manchester medical society

  A review of comparative incidence of infective endocarditis in bioprosthetic vs mechanical valves (1) can only be complete if there is a clear statement of the criteria for the diagnosis of infective endocarditis. An important characteristic of prosthetic valve endocarditis is that "the diagnosis[of endocarditis] is more difficult in the presence of a prosthetic valve when compared with a native valve" due to the fact that "the Duke criteria have been shown to be less helpful in prosthetic valve endocarditis because of lower sensitivity in this setting"(2). Furthermore,
  the diagnostic accuracy of some imaging modalities is suboptimal in prosthetic valve endocarditis(3). According to the latter review , among patients with suspected prosthetic valve endocarditis sensitivity of transthoracic echocardiography can be as low as 17%-36%. For transoesophageal echocardiography(TOE) that parameter increases to 82-96%, the latter statistic comparable to the sensitivity associated with 18 Fluorodeoxyglucose positron emission tomography/CT(PET/CT). Also in the context of prosthetic valve endocarditis, TOE and PET/CT also have comparable specificities in the range 80-96%(3). The major limitation of TOE is that it is invasive and also operator dependent. By contrast PET/CT not only increases the sensitivity of the modified Duke criteria from 70% to 97%(without affecting specificity) but that modality also identifies metastatic septic embol...

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  A review of comparative incidence of infective endocarditis in bioprosthetic vs mechanical valves (1) can only be complete if there is a clear statement of the criteria for the diagnosis of infective endocarditis. An important characteristic of prosthetic valve endocarditis is that "the diagnosis[of endocarditis] is more difficult in the presence of a prosthetic valve when compared with a native valve" due to the fact that "the Duke criteria have been shown to be less helpful in prosthetic valve endocarditis because of lower sensitivity in this setting"(2). Furthermore,
  the diagnostic accuracy of some imaging modalities is suboptimal in prosthetic valve endocarditis(3). According to the latter review , among patients with suspected prosthetic valve endocarditis sensitivity of transthoracic echocardiography can be as low as 17%-36%. For transoesophageal echocardiography(TOE) that parameter increases to 82-96%, the latter statistic comparable to the sensitivity associated with 18 Fluorodeoxyglucose positron emission tomography/CT(PET/CT). Also in the context of prosthetic valve endocarditis, TOE and PET/CT also have comparable specificities in the range 80-96%(3). The major limitation of TOE is that it is invasive and also operator dependent. By contrast PET/CT not only increases the sensitivity of the modified Duke criteria from 70% to 97%(without affecting specificity) but that modality also identifies metastatic septic emboli(3). The caveat is that false positives may occur soon after prosthetic valve implantation(due to reactive inflammatory activity) whereas false negatives may be attributable to previous antibiotic therapy or attributable to small vegetations(3). Further support for PET/CT comes from a study of 303 subjects who underwent PET/CT evaluation for suspected aortic valve endocarditis and for suspected infection of ascending aortic prostheses . 141 had bioprosthetic valves, and 10 had mechanical valves. 115 had native valves. The rest had ascending aortic prostheses. Among the 188 with an eventual diagnosis of either prosthetic valve endocarditis or an ascending aortic implant infection the sensitivity, specificity, and positive and negative predictive values of PET/CT amounted to 93%, 90%, 89%, and 94%, respectively. Among the 115 subjects with native valve endocarditis the corresponding values were 22%, 100%, 100%, and 66%(4).
  Fungal endocarditis, for which prosthetic valve implantation is also a risk factor, poses additional challenges because there are no diagnostic criteria specific to fungal endocarditis. Potential imaging modalities in this context include PET/CT, complemented by magnetic resonance imaging of the head in patients who have embolic phenomena, and abdominal computed tomography for suspected intra abdominal emboli(5).
  Although it is an important caveat that PET/CT is expensive and not widely available, and that preprocedural fasting and dietary regimes still have to be optimised(6) , the reality is the the use of PET/CT has highlighted the recognition that there is a huge potential for underdiagnosis of prosthetic valve endocarditis with the use of less expensive but more widely available technologies, thereby undermining any attempts to evaluate the prevalence of prosthetic valve endocarditis, let alone its prevalence in subgroups of prosthetic valve recipients.
  I have no funding and no conflict of interest
  References
  (1) Anantha-Naranayan M., Reddy YNV., Sundaram V et al
  Endocarditis risk with bioprosthetic and mechanical valves: systematic review and meta-analysis
  Heart doi 10.1136/heartjnl-2020-316718
  (2)Bruun NE., Habib G., Thuny F., Sogaard P
  Cardiac imaging in infectious endocarditis
  Eur heart J 2014;35:624-632
  (3)Ivanovic B., Trifunovic D., Matic S., et al
  Prosthetic valve endocarditis- A trouble or a challenge?
  Journal of Cardiology 2019;73:126-133
  (4) de Camargo RA., Bitencourt MS., Monaghetti JC et al
  The role of 18 Fluorodeoxyglucose positron emission tomography/computed tomography in the diagnosis of left-side endocarditis: native vs prosthetic valves endocarditis
  Clinical Infectious Diseases 2020;70:583-595
  (5)Pasha A., Lee JZ., Low S-W., et al
  Fungal endocarditis : Update on diagnosis and management
  Am J Med 2016;129:1037-1043
  (6) Sanbuceti G., Morbelli S., Orengo AM., Bauckneht M., Marini C
  18F-Fkuorodeoxyglucose imaging of inflammation Ready to represent a stndard in diagnosing endocarditis?
  Circ Cardiovasc Imaging 2017;10:e006185

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  Conflict of Interest:
  None declared.

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