Infective Endocarditis Risk Still High After Invasive Procedures

June 26, 2018

The risk for infective endocarditis climbs significantly after many invasive therapeutic and diagnostic procedures and is especially high after some common ones, such as bronchoscopy and coronary angiography, conclude investigators of a large observational study that included cases from 1998 to 2011.

The analysis, which excluded dental procedures in Sweden, invites at least a partial reappraisal of guidelines from a decade ago that dramatically cut reliance on antibiotic prophylaxis with dental and many nondental invasive procedures, contends a report published June 11 in the Journal of the American College of Cardiology.

"Apart from a potential reconsideration of antibiotic prophylaxis before certain particularly high-risk procedures, our findings also suggest that further improvement of aseptic measures before and during invasive procedures to minimize the excess risk for infective endocarditis is of crucial importance," write the authors, led by Imre Janszky, MD, PhD, from the Norwegian University of Science and Technology, Trondheim.

"Among therapeutic procedures, cardiovascular operations, especially coronary revascularizations; procedures on skin and wounds; chronic hemodialysis; blood transfusion; and various noncardiovascular operations carried the highest risk," the authors write.

"Among diagnostic procedures, bone marrow puncture, coronary angiography, and some transluminal endoscopies, especially bronchoscopy, were the most important," they add.

"We believe increased awareness of the heightened risk in the vulnerable period after these procedures might lead to earlier diagnosis with better chance for successful therapy and for avoiding the feared complications of the disease," Janszky told | Medscape Cardiology.

"Thus, for patients at high risk for infective endocarditis, in case of relevant symptoms, clinicians should look for a recent history of invasive procedures."

The analysis looked at 7013 adults treated for endocarditis in Sweden throughout the 14-year period, comparing the occurrence of invasive procedures in the preceding 12 weeks with those in a 12-week period a year earlier.

For some of the procedures associated with a sharply elevated risk for endocarditis in the analysis, antibiotic prophylaxis had previously been recommended prior to a guideline re-evaluation a decade ago, but was not recommended in the guideline revisions from 2007 to 2009, an accompanying editorial observes.

They include esophageal endoscopy, genitourinary endoscopies, and bronchoscopy, note the editorialists, with lead author Martin H. Thornhill, MBBS, BDS, PhD.

"At face value, the implication is that virtually any inpatient or outpatient invasive procedure may be a trigger for subsequent infective endocarditis. Although this may be correct, some caution is required," they write, given the study's limitations. For example, "observational data cannot establish causality." 

Still, they write, "this work is by far the largest study to address the link between invasive medical procedures and subsequent infective endocarditis. It is the highest-quality data available to support an association between invasive medical procedures and infective endocarditis."

Table 1. Relative Risk for Infective Endocarditis After Invasive Outpatient Procedures

Procedure Relative Risk (95% Confidence Interval)
Gastroscopy 2.50 (1.59 - 3.94)
Colonoscopy 2.89 (1.35 - 6.17)
Dialysis 4.33 (2.10 - 8.95)
Bone marrow puncture 4.33 (1.24 - 15.21)
Coronary angiography 4.75 (1.61 - 13.96)
Bronchoscopy 5.00 (1.10 - 22.82)
Transfusion 5.50 (1.22 - 24.80)


Additionally, the researchers compared the risk for infective endocarditis in the first 7 years vs the second 7 years of the observation period, corresponding roughly with the times before and after the guideline shift toward more conservative antibiotic prophylaxis.

"The risk elevation was somewhat higher in the second half when antibiotic prophylaxis was probably less frequent," Janszky said.

The group calculated a number needed to treat of 476 high-risk patients receiving prophylactic antibiotics before an invasive procedure to prevent 1 case of infective endocarditis. The analysis assumed antibiotics always conferred protection.

"The number needed to treat is considerably lower for some particularly high-risk procedures. For example, these numbers were 83 and 40 for bronchoscopy in our main and secondary analyses, respectively," the group writes.

"Our results certainly suggest that the infectious endocarditis risk is substantially increased after some procedures," Janszky commented. But it isn't enough on its own to change the guidelines.

"Making a guideline on whether to recommend antibiotics and before which procedures is a complex process, and our results have to be viewed in light of other studies with different designs and settings but also of cost-benefit considerations."

On the other hand, write Thornhill and colleagues in the editorial, "If the breadth of procedures associated with increased risk is confirmed by further studies, this will raise important questions for guideline committees about the benefits of recommending antibiotic prophylaxis prior to some of these procedures."

But "broadening the scope of antibiotic prophylaxis to include all of these procedures is unlikely to be the solution. At least for those procedures where sterility should be easy to achieve and maintain, the solution is more likely to lay with improved sterile technique, infection control procedures and identifying systematic approaches for reducing health care–associated bacteremia, rather than necessarily advocating antibiotic prophylaxis."

Bicuspid Aortic Valve and Mitral Valve Prolapse  

In a separate report also published June 11 in the Journal of the American College of Cardiology, patients with bicuspid aortic valve (BAV) and mitral valve prolapse (MVP) who have infective endocarditis (IE) tend to show a different microbiologic profile than other patients with IE, and their infection is more likely to be of dental origin.  

Antibiotic prophylaxis isn't currently called for in patients with BAV or MVP, but their clinical course, including risk for cardiac complications, if IE develops is on par with that of other patients with IE who have established indications for antibiotic prophylaxis, the authors conclude.  

"Based on these indirect data, we suggest that BAV and MVP should be considered high-risk IE cardiac conditions, and that [an ] IE antibiotic-prophylaxis indication should be reconsidered for this group of patients," write the authors, led by Isabel Zegri-Reiriz, MD, PhD, Hospital Universitario Puerta de Hierro, Madrid, Spain.

The results come from a 3208 patients with IE in the 31-hospital the Spanish Collaboration on Endocarditis—Grupo de Apoyo al Manejo de la Endocarditis Infecciosa en España (GAMES) registry.

Those without BAV or MVP were classified as high-risk for IE (history of IE or having prosthetic valves, unrepaired cyanotic congenital heart disease, repaired congenital heart disease or surgery for such disease within the past 6 months) or low-to-moderate IE risk.

Table 2. Rates of IE-Related Risks and Adverse Events by Patient Category


Variable BAV (n = 54) (%) MVP (n = 89) (%) Low to Moderate IE Risk (n = 1839) (%) High IE Risk (n = 1226) (%)
Cardiac complicationsa 50 47.2 30.6b 44.8
Heart failure 40.7 34.8 45.0 38.5
In-hospital death 5.6 10.1 28.3b 29.0b
Viridans group IE 35.2 39.3 15b 12.1b
IE of suspected odontologic origin 14.8 18.0 5.8b 6.0b
IE of suspected oral origin 42.6 46.1 16.8b 14.6b
aCardiac complications consist of abscess, fistula, perforation, pseudoaneurysm, or prosthetic dehiscence.

b P < .01 vs BAV and MVP.


The findings for patients with BAV and MVP who had IE "revealed an aggressive clinical course with a similar proportion of IE complications to that of IE patients with high-risk cardiac conditions, and more intracardiac complications than in patients of the low-risk and intermediate-risk groups," write the authors.

The author of an accompanying editorial agrees the data suggest BAV and MVP "have a higher than appreciated risk for IE and might benefit from AP [antibiotic prophylaxis], which is against current guideline advice."

Current risk categories "may be insufficiently precise. Even within a diagnosis, there may be subcategories of risk," writes John B. Chambers, MD, Guy's and St. Thomas' Hospitals, London, United Kingdom. He proposes a scoring system for determining appropriateness of antibiotic prophylaxis based on IE risk factors, the risks of such prophylaxis itself, and stratification of risk for death from IE.

"Meanwhile, professional bodies should discuss extending AP to patients with BAV or MLP [mitral prolapse] with moderate or more regurgitation who are having high-risk procedures such as dental scaling or extractions."

Janszky and coauthors, Zegri-Reiriz and coauthors, and Chambers report that they have no relevant disclosures. Thornhill reports no relevant relationships; disclosures for his coauthors are in the publication.

J Am Coll Cardiol. Published online June 11, 2018. Janszky abstract, Thornhill editorial, Zegri-Reiriz abstract, Chambers editorial

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