Troubling Trends for Infective Endocarditis in Dialysis Patients

Patrice Wendling

April 01, 2021

The occurrence of endocarditis in hemodialysis patients may be significantly higher than previously thought, but it is as lethal as ever, a new observational study suggests.

Researchers examined data from patients with infective endocarditis from 2000 to 2006 in the International Collaboration on Endocarditis (ICE) Prospective Cohort Study and from 2008 to 2012 in the ICE-Plus databases. Overall, sites from 30 countries participated in either cohort.

Of the 6691 patients with sufficient data, 553 patients, or 8.3%, were receiving chronic hemodialysis. Although that's significantly higher than the 2.0% to 6.0% observed in previous reports, "the 8.3% was kind of expected because it reflects the complexity of patients in reference centers for cardiac surgery," colead author Juan M. Pericàs, MD, PhD, MPH, University of Barcelona, Spain, told | Medscape Cardiology.

The main risk factor for endocarditis in the dialysis group was an in-dwelling catheter, present in 48.1% of patients, although arteriovenous fistulas were also common (34.2%) and shouldn't be overlooked as a possible source of bacteremia, even if it doesn't appear infected, the authors note. Staaphylococcus aureus was the most common causative organism in dialysis patients (48.7%), followed by Enterococci (15.4%).

In-hospital and 6-month mortality rates were almost twice as high in dialysis patients as in nondialysis patients (30.4% vs 16.9% and 39.8% vs 20.7%, respectively; P = .001 for both comparisons).

In multivariate analysis, persistent bacteremia (odds ratio [OR], 3.98; P = .01) and Charlson Comorbidity Index score (OR, 1.32; P = .04) predicted in-hospital mortality. Risk factors for 6-month mortality were Charlson score (hazard ratio [HR], 1.26; P = .001), central nervous system emboli and other systemic emboli (HR, 3.11; P < .001), persistent bacteremia (HR, 1.79; P = .02), and acute-onset heart failure (HR, 2.37; P < .001).

Although it didn't enter into the multivariate model, North America was significantly associated with lower in-hospital mortality (compared with Europe, for example, 23.2% vs 38.3%). North Americans were a median of 10 years younger than European patients and more than 5 years younger than patients from other regions. But at the same time, relapse rates were higher in North America than in other regions (OR, 2.33; P = .06).

"It's true that ours is not an epidemiology-based study that could be interpreted as really nationwide, representative peers, but it's shocking to see how North America is so different from other continents," Pericàs said.

In all regions, patients not on dialysis were more likely to receive cardiac surgery. In-hospital mortality in the dialysis group undergoing surgery reached 31.5%, compared with 29.7% in the group not having surgery. New moderate or severe valve regurgitation (OR, 1.90; P = .003) and paravalvular abscess (OR, 2.24; P = .05) were risk factors for surgery, according to the study, published this week in the Journal of the American College of Cardiology.

The authors, co-led by Jaume Llopis, MD, PhD, also from the University of Barcelona, write that available evidence points to worse postsurgical outcomes in hemodialysis patients and that the role of cardiac surgery in hemodialysis infective endocarditis patients "remains controversial and further research on optimized appraisals for the indication of cardiac surgery in these patients are warranted."

Despite the developments in cardiac surgery, including transesophageal echocardiography, and better antibiotic combinations, average mortality is still about 25% in reference centers, observed Pericàs. "The endocarditis team has been proposed as the way of circumventing this situation and improving the circuits of referral to cardiac surgery. Early assessment and early surgery are the way forward for hemodialysis patients, but also for other patients traditionally considered high risk, such as septic shock, cardiogenic shock."

Part of the problem is that irrespective of the severity of the endocarditis episode, if a patient is on dialysis, the risk score will be very high, so surgeons may be reluctant to operate, Pericàs added. "But we know that cardiac surgery, if performed in the best conditions possible — mainly in the context of an endocarditis team with very good collaboration between clinicians and surgeons — can improve the prognosis of these patients."

In an accompanying editorial, Neel R. Sodha, MD, Brown University Rhode Island Hospital, Providence, notes that the incidence of endocarditis and end-stage renal disease are on the rise, but that two large surgical series reported by the Cleveland Clinic and the University of Michigan show operative mortality rates of 13% and 14%, respectively, in dialysis patients with endocarditis.

Taken together with the present study, the findings "highlight the high operative mortality in this patient group and bring renewed attention to redefining appropriate indications for surgery for this subset of patients rather than applying current general guidelines," he writes.

Although the ICE database represents the largest available international dataset with prospectively collected standardized clinical information and follow-up, the patients were from institutions with a particular interest in endocarditis and more than 70% were from Europe and North America, which may limit true epidemiological inferences, Sodha says.

Other limitations are that more than 25% of the sample was lost to follow-up at 6 months, which could potentially limit midterm outcome interpretation, and funding for the database ended in 2012, which limits ascertainment of more current trends and outcomes.

The study was supported by the National Institutes of Health, Red Española de Investigación en Patología Infecciosa, and Instituto de Salud Carlos III. Senior author Jose M. Miró received a personal research grant from the Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain, during the period from 2017 to 2019. All other authors and Sodha reported having no relevant disclosures.

J Am Coll Cardiol. 2021;77:1629-1640, 1641-1643. Full text, Editorial

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