In October of 2015, Circulation published updated guidelines on the diagnosis and management of infective endocarditis;  this was updated from the prior guidelines that were published in 2005. Although much of the previous recommendations remained unchanged, a few notable differences were present. The 2015 guidelines suggest that patients with endocarditis be transferred to an institution where a multidisciplinary team consisting of infectious disease specialists, cardiologists, and cardiac surgeons are available, in order to help assist in the accurate diagnosis and management of this often elusive disease. The guidelines now imply that transthoracic echocardiography (TTE) should be done up front for all patients with concerns for underlying infective endocarditis, regardless of the degree of suspicion of disease; the prior recommendations were to consider going directly to trans-esophageal echocardiography (TEE) if suspicion for endocarditis was high. If echocardiography is initially negative for evidence of endocarditis and clinical suspicion remains high, the recommendation is now to repeat imaging in 3-5 days, rather than the 7-10 days which was outlined in the 2005 guidelines. These new guidelines also do make note of the differences between 2D and 3D echocardiography (3D echocardiography is more sensitive, but tends to provide an overestimation of vegetation size), and outline the potential role of cardiac CT and MRI, PET CT and SPECT imaging as adjunctive tools in the diagnosis of infective endocarditis, especially when cardiac hardware is in place. Prompt acquisition of diagnostic imaging and subsequent initiation of therapy are also recommended; early surgery, when indicated, is also now favored rather than delayed intervention. Lastly, combination beta-lactam therapy is now recommended as alternative management of both native and prosthetic valve endocarditis due to enterococcal organisms, although the majority of the data regarding dual beta lactam therapy has been associated with efficacy regarding E. fecalis isolates, rather than E. faecium.

One issue that is not well defined in the new guidelines is how to effectively manage patients who develop infective endocarditis in the setting of active injection drug use. Injection drug use is becoming a more common risk factor for endocarditis, and is associated with approximately 2-4 cases per 1000 injection drug use years. These patients are more likely to develop right-sided cardiac involvement when infected, which is often associated with additional complications, including septic emboli and right heart failure. In addition, these patients are often unable to be safely sent home after their hospitalization given that treatment for endocarditis usually requires long-term intravenous antibiotics, necessitating the need for catheter placement, which could then be manipulated or abused by the patient if left to their own devices in an unsupervised setting. This results in either suboptimal therapy with oral regimens, or transfer of the patient to skilled care facilities. Lastly, cardiac surgery for these patients is often a frustrating ordeal, as the cost, time and effort associated with providing valvular surgery often ends with the patient re-infecting themselves again once they go back into the same environment in which their drug use was occurring. These patients are more likely to not follow up in the outpatient setting, and are less likely to remain compliant when oral medications are given for their infection.

All of these issues pose a major dilemma; how do we address the problem of curing patients of both their endocarditis and the drug use that led to their infection in the first place? The new guidelines talk about consideration for drug rehab for patients who come in with endocarditis that are found to be actively using drugs. Currently, this is not universally implemented across hospitals in the U.S, and perhaps further studies will be able to reinforce the need for mandatory drug rehabilitation referral for all patients coming in with endocarditis secondary to drug use. The new guidelines simply state that if possible, surgery should be avoided in patients who develop endocarditis in the setting of active drug use, however this clearly is associated with ethical conflicts, especially if it is known that proceeding with surgery could save the patient’s life. Initiating mandatory drug rehab and limiting the number of surgeries provided for these patients raises new ethical and financial issues which will be difficult to implement unless further data supports their efficacy and shows an overall reduction in cost to hospitals and health-care providers, without a significant impact in clinical outcomes.

As of yet, solutions to this problem are not well defined, and as stated above, perhaps further studies on this specific patient population are needed to shed light on what interventions would be effective in addressing this issue. Likely, a combination of interventions, including prompt treatment of their infection, referral to drug rehab, access to social and financial support mechanisms and better outpatient monitoring and follow up will be critical in improving outcomes among these patients.

REFERENCES:

• Hussey, HH, Katz S. Infections resulting from narcotic addition; report of 102 cases. Am J Med, 1950:9:186
• Sande MA, Lee BL, Mills J, et al. Endocarditis in intravenous drug users. In: Infective Endocarditis, Kaye D (Ed), Raven Press, New York City 1992. p.345.
• Weinstein WL, Brusch JL. Infective endocarditis, Oxford University Press, New York City 1996.
• Spijkerman IJ, van Ameijden EJ, Mientjes GH, et al. Human immunodeficiency virus infection and other risk factors for skin abscesses and endocarditis among injection drug users. J Clin Epidemiol 1996; 49:1149.
• Welton DE, Young JB, Gentry WO, et al. Recurrent infective endocarditis: analysis of predisposing factors and clinical features. Am J Med 1979; 66:932.
• PUBMED citation for endocarditis guidelines

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