Prosthetic valve endocarditis

Prosthetic valve endocarditis

Prosthetic valve endocarditis (PVE) is a serious disease with unfavourable outcome. Staph. aureus is the commonest organism in prosthetic valve endocarditis. More complications like paravalvar leak and abscess formation are more common with prosthetic valve endocarditis. Fortunately, the incidence of early PVE has come down, due to better perioperative care and infection control.

There is a difference between mechanical and bioprosthetic valves. The mechanical valves do not allow the adherence of the organism unless there is a thrombus. The infection is most often in the region of the annulus and causes myocardial invasion and abscess, but is less likely to produce valvular obstruction. More of paravalvular problems are likely with mechanical prosthesis. Bioprosthetic valves have a higher rate of infections and resembles that of native valve endocarditis.

Transthoracic echocardiography has a yield of only 15% in mechanical prosthesis as it is the annulus which is most often involved. Transesophageal echocardiography (TEE) is much better for detection of vegetations and even small periprosthetic leaks. Abscesses and unstable prosthesis are better detected by TEE.

3D echocardiography and CT are evolving modalities for diagnosis of PVE. PCR has a high yield for detection of PVE compared with conventional blood culture.

Staph and fungal endocarditis is more common with early PVE. The cutoff time for diagnosis of early PVE is being extended from 60 days to one year. Surgical therapy has an edge over medical therapy for the treatment of PVE. Large vegetations is one of the reasons, while mechanical complications and fungal endocarditis are better treated surgically. Biofilm over the valve prevent penetration of antibiotics. Micro abscesses which are more common with and staph aureus endocarditis also prevent proper medical treatment. Rifampicin is one drug which can penetrate the biofilm and the microabscesses. Vancomycin and oxacillin are two good drugs commonly used in the treatment of prosthetic valve endocarditis. Gentamicin is also quite useful. Linezolid is often used as a bailout drug in very sick patients who cannot be given vancomycin due to renal problems.

International Collaboration on Endocarditis (ICE) from Duke University, the pioneers in endocarditis research reported that a little less than half of the thousand odd patients with prosthetic valve endocarditis underwent early surgery while the rest underwent medical therapy [1]. They found that after adjustment for clinical factors and survivor bias, early surgery for prosthetic valve endocarditis was not associated with lower in hospital or one year mortality. But prosthetic valve endocarditis did have a high one year mortality rate.

We had the opportunity to be part of ICE from Calicut Medical College (currently renamed Govt. Medical College, Kozhikode) [2].

A comparison of prosthetic valve endocarditis in transcatheter aortic valve replacement (TAVR) vs surgical aortic valve replacement (SAVR) has been published [3]. Pooled cohort of all patients in PARTNER 1 and PARTNER 2 trials were analyzed, with a total of 8530 patients among whom there were 107 cases of prosthetic valve endocarditis. They found no difference in the incidence of prosthetic valve endocarditis between TAVR and surgical AVR. Predictors in both groups were renal, lung and liver disease. Most cases in both groups occurred between 31 days and one year. Most important finding was that prosthetic valve endocarditis was associated with a more than four fold risk of death. In this study, early prosthetic valve endocarditis was defined as before 30 days, 31 days to one year as intermediate and beyond 1 year as late.

References

1. Lalani T, Chu VH, Park LP, Cecchi E, Corey GR, Durante-Mangoni E, Fowler VG Jr, Gordon D, Grossi P, Hannan M, Hoen B, Muñoz P, Rizk H, Kanj SS, Selton-Suty C, Sexton DJ, Spelman D, Ravasio V, Tripodi MF, Wang A; International Collaboration on Endocarditis–Prospective Cohort Study Investigators. In-hospital and 1-year mortality in patients undergoing early surgery for prosthetic valve endocarditis. JAMA Intern Med. 2013 Sep 9;173(16):1495-504.
2. Chu VH, Miro JM, Hoen B, Cabell CH, Pappas PA, Jones P, Stryjewski ME, Anguera I, Braun S, Muñoz P, Commerford P, Tornos P, Francis J, Oyonarte M, Selton-Suty C, Morris AJ, Habib G, Almirante B, Sexton DJ, Corey GR, Fowler VG Jr; International Collaboration on Endocarditis-Prospective Cohort Study Group. Coagulase-negative staphylococcal prosthetic valve endocarditis–a contemporary update based on the International Collaboration on Endocarditis: prospective cohort study. Heart. 2009 Apr;95(7):570-6.
3. Summers MR, Leon MB, Smith CR, Kodali SK, Thourani VH, Herrmann HC, Makkar RR, Pibarot P, Webb JG, Leipsic J, Alu MC, Crowley A, Hahn RT, Kapadia SR, Tuzcu EM, Svensson L, Cremer PC, Jaber WA. Prosthetic Valve Endocarditis After TAVR and SAVR: Insights From the PARTNER Trials. Circulation. 2019 Dec 10;140(24):1984-1994.