Author + information
- Published online November 12, 2018.
- aDepartment of Medicine, Division of Cardiology, University of California, San Francisco School of Medicine, San Francisco, California
- bFaculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
- ↵∗Address for correspondence:
Dr. Ann Bolger, Zuckerberg San Francisco General Hospital, Division of Cardiology, 1001 Potrero Avenue, San Francisco California 94110.
Endocarditis is dread and unpredictable. As medical and dental providers, we are all long used to worrying about it. The numbers of patients that we see who are at risk for infective endocarditis (IE) by virtue of native or prosthetic valve disease, implanted cardiac devices, congenital heart disease, or advancing age is increasing every year. Strategies for rapid and reliable diagnosis of IE and its management have improved, but prevention remains paramount. It seemed to make sense to anticipate when the guilty bacteremia causing IE might possibly occur and throw antibiotics in the path of that oncoming threat. As a physician who has seen much IE and is an accomplished worrier on behalf of my patients at risk for IE, I miss the days when I felt reassured by a single dose of a generally well-tolerated medication fending off such catastrophes.
The difficulty being, of course, that the effectiveness of antibiotic prophylaxis (AP) against IE has never been proven. In 2007, the most recent guidelines for the prevention of IE were published (1). Diligent review of all available published reports regarding AP against IE led to the conclusion that there was no evidence that AP is effective (2). Other international professional societies, including the European Society of Cardiology and the National Institute for Health and Care Excellence (NICE), reached the same conclusion (3,4). In the United States, the 2007 guidelines provided a major departure from prior recommendations by suggesting that only the patients at highest risk of worst IE outcomes should continue to receive AP.
Following this marked shift in the guidelines, researchers and clinicians have been on the lookout for signals of increases in IE in the population that might indicate adverse impacts of the changes. Since the publication of the 2007 guidelines, there have been many studies performed in multiple populations seeking those signals. It remains inconclusive: results have been mixed, even among analyses using the same data, and affected by limitations in methods or available data (5–7).
Two limitations have persistently challenged the ongoing efforts to seek adverse signals. The first is not knowing the degree to which the guidelines are actually followed. Second, inadequate data on causative organisms interfere with determining whether any changes in IE are attributable to an increase in infections with odontogenic streptococci targeted by the AP strategy.
The paper by Thornhill et al. (8) in this issue of the Journal takes direct aim at the first of these limitations. It explores who is and is not receiving antibiotic prophylaxis according to current recommendations and will prove very helpful in interpreting potential signals of increasing IE. The authors used an extensive database to determine trends in AP and IE during an 18-month transition period following the publication of the scientific statement, and then for 7 years afterwards when they expected practice to have incorporated the published guidelines. AP practices in this population did not closely mirror the recommendations. There was a decline, but not cessation, in AP provided to patients in the moderate-risk category. More surprisingly, the authors found that the provision of AP to high-risk patients fell by 20% after the 2007 guidelines, contrary to their recommendations. In a worrisome trend, in that high-risk group, the rate of IE increased, compared with rates predicted by the incidence trend before 2007.
Taken at face value, these results suggest that this failure to comply with the AP guidelines may have contributed to potentially avoidable cases of endocarditis in the patients most at risk. If these 2 trends in AP and IE were proven to be linked in a cause and effect manner, these results would strike both fear and hope into the hearts of dedicated IE worriers—fear that some patients at high risk have been inadequately protected from IE due to lack of compliance with AP recommendations, and hope that there might finally be some indication that AP is actually effective in avoiding some cases of endocarditis.
The difficulty is that we do not know whether excess IE in the high-risk group was due to organisms that would have been affected by AP had it been used. Without knowledge of changes in the proportions of oral streptococcal versus other causative organisms, cause and effect cannot be intuited from these data. Nonstreptococcal endocarditic infections have increased significantly (9). Without knowing how many of the IE cases were in fact caused by organisms targeted by the recommended timing and type of prophylactic antibiotics, it is not possible to interpret these data in a way that supports causality.
At this point, there is no respite from worrying about preventing IE. For our patients’ sakes, thoughtful risk assessment, clear communication of that risk, and commonsense guidance on oral health and avoiding preventable bacteremia should be the core of our prevention strategy. Even when AP is recommended, counseling about oral hygiene, responding to unexplained fever by presenting for evaluation, consideration of blood cultures before initiating antibiotic use, and vigilance regarding skin break down or vascular entry are critically important. Studies on changing IE incidence that incorporate prophylaxis-related practices and bacteriology will be the most useful in improving risk-based IE prevention practices in the future.
↵∗ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
Dr. Bolger has reported that she has no relationships relevant to the contents of this paper to disclose.
- 2018 American College of Cardiology Foundation
- Wilson W.,
- Taubert K.A.,
- Gewitz M.,
- et al.
- Habib G.,
- Hoen B.,
- Tornos P.,
- et al.
- ↵National Institute for Health and Care Excellence (NICE). Prophylaxis Against Infective Endocarditis: Antimicrobial Prophylaxis Against Infective Endocarditis in Adults and Children Undergoing Interventional Procedures. NICE Clinical Guideline No 64. March 2008. London, UK: NICE.
- Pant S.,
- Patel N.J.,
- Deshmukh A.,
- et al.
- DeSimone D.C.,
- Tleyjeh I.M.,
- Correa de Sa D.D.,
- et al.
- Kazi D.S.,
- Bolger A.F.
- Thornhill M.H.,
- Gibson T.B.,
- Cutler E.,
- et al.
- Vogkou C.T.,
- Vlachogiannis N.I.,
- Palaiodimos L.,
- Kousoulis A.A.