Endocarditis Tied to Whopping Mortality Risk Within Years

Danish hospitals logged alarmingly high mid-term mortality rates in infective endocarditis (IE) despite improvements in identifying culprit pathogens in recent years, sending a warning to other centers worldwide.

The IE death rates were grim during the median 2.3 years of follow-up, at 58.5% across Streptococcus species and 74.4% for Enterococcus species, according to researchers led by Lauge Østergaard, MD, PhD, of the University of Copenhagen and Rigshospitalet, Denmark.

The most common cause of IE — Staphylococcus aureus, accounting for some 28% of IE in the nationwide registries from 2010-2017 — had a 70.1% mortality rate over follow-up, the researchers reported in the manuscript published in the Journal of the American Heart Association.

In an accompanying editorial, Christopher Primus, MBBS, and Simon Woldman, MD, both of St. Bartholomew’s Hospital in London, called these mortality rates “astounding.”

“The very high rates of medium-term mortality are a serious concern, and as a community we must strive to identify and address modifiable risk factors to improve outcome. To achieve this, we must innovate in diagnostics, adopt a mindset of active consideration and adoption of early surgery, and develop robust pathways that facilitate working in expert teams,” the editorialists suggested.

They said that, despite the high morbidity and mortality, IE’s rarity may partly explain why hospitals in and outside the present report have been ill-equipped to deliver rapid diagnostics regarding culprit microorganisms.

Indeed, IE studies from the U.S. — also reporting S. aureus as the most frequent microbiological cause — have been marred by approximately a quarter to a third of cases having no attributable culprit pathogen, Østergaard and colleagues noted.

The frequency of IE cases remained relatively unchanged over time in Østergaard’s study. However, the proportion of blood culture-negative IE declined during the study period from 24.1% to 18.4% (P=0.005 for trend), and these cases were associated with 18.6% in-hospital mortality and 62.4% mortality over the entire follow-up period.

For their study, the authors identified 4,123 people with first-time IE based on Danish databases. The cohort was 67.6% men, with a median age of 71.8 years.

In the nationwide registries from 2010 to 2017, S. aureus was both the most frequent cause of IE (28.1%) and the deadliest in terms of in-hospital mortality (28.2%). Right behind were other causes of IE:

• Streptococcus species: 26.0% of cases, in-hospital mortality 11.1%
• Enterococcus species: 15.5% of cases, in-hospital mortality 16.8%
• Coagulase-negative staphylococci (CoNS): 6.2% of cases, in-hospital mortality 16.6%
• Other microbiological causes: 5.3% of cases, in-hospital mortality 13.9%

Over the full follow-up period, CoNS IE had a 62.4% mortality rate, IE of other microbiological cause had a 60.6% rate, and blood culture-negative IE a rate of 62.4%.

Heart valve procedures, cardiac implantable electronic device placement, dialysis, and IV drug use are among the established risk factors for IE.

By IE subgroups, patients with S. aureus IE and CoNS IE tended to have more renal disease, whereas peers with Enterococcus species were older and more often had a prosthetic heart valve implanted.

The investigators acknowledged that the Danish data lacked clinical characteristics such as symptoms and echocardiography findings. Contamination of cultures may also have affected results, they warned.

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