PerspectiveIn the Journals

Early valve surgery did not affect mortality in S. aureus endocarditis

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December 4, 2014

Early valve surgery did not reduce 1-year mortality among patients with Staphylococcus aureus prosthetic valve infective endocarditis, according to recent study data.

“Consequently, we believe that decisions about early valve surgery [in these patients] should be individualized for each patient and based on careful clinical multidisciplinary evaluation, exactly as in other patients with infective endocarditis,” the researchers wrote in Clinical Infectious Diseases. “Further research to define the effect and optimize the timing of surgery in patients with S. aureus prosthetic valve infective endocarditis and more generally prosthetic valve infective endocarditis should in the future rely on well-designed multicenter interventional trials.”

Catherine Chirouze, MD, of Hôpital Jean Minjoz in Besançon, France, and colleagues examined data from the International Collaboration on Endocarditis – Prospective Cohort Study. There were 5,668 cases prospectively recorded from January 2000 to December 2006. The researchers excluded cases in IV drug users, cases of right-sided valve infective endocarditis or native valve infective endocarditis and cases with missing data. Among the 747 patients with left-sided prosthetic valve infective endocarditis (PVIE), 168 were due to S. aureus and underwent evaluation.

Patients who had early valve surgery (44.3%) showed lower 1-year mortality rate than patients who did not receive early valve surgery (33.8% vs. 59.1%; P=.001). However, the association did not persist in a multivariate, propensity-adjusted model (RR=0.67; 95% CI, 0.39-1.15). The researchers identified three variables associated with 1-year mortality: age (per 1-year increment, HR=1.03; 95% CI, 1.01-1.05), stroke (time-dependent HR=2.56; 95% CI, 1.62-4.05) and congestive heart failure (HR=2.06; 95% CI, 1.29-3.3).

“Although guidelines may help clinicians decide whether and when patients with infective endocarditis should undergo surgery, such decisions can be extremely difficult in individual and unique patients, and particularly in patients with PVIE,” the researchers wrote. “Patients with S. aureus PVIE who undergo early valve surgery are younger, have more severe cardiac complications and appear to have significantly lower in-hospital and 1-year mortality rates than patients with S. aureus PVIE who do not undergo early valve surgery. However, early valve surgery was not an independent predictor of better outcome.”

Disclosure: One researcher has received consulting honoraria or research grants from Abbott, Boehringer-Ingelheim, Bristol-Myers Squibb, Cubist, Novartis, GlaxoSmithKline, Gilead Sciences, Pfizer, Roche, Theravance and ViiV Healthcare.

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Michael Calderwood

Michael Calderwood

Chirouze et al used the International Collaboration on Endocarditis (ICE) – Prospective Cohort Study (PCS) database to examine predictors of mortality in 747 patients with left-sided prosthetic valve infective endocarditis (PVIE): 168 cases involving Staphylococus aureus and 579 cases involving a different bacteria. As discussed in the editorial by Karchmer and Bayer, which accompanied this paper, there remains a debate as to whether S. aureus as the etiology of PVIE is an indication to perform surgery independent of the classic indications for surgical intervention. On univariate analysis, the researchers found that the patients who underwent surgery within 60 days of presentation [ie, early valve surgery (EVS)] were younger (P=0.04), less likely to be on hemodialysis (P=0.04), and more likely to have a longer duration of symptoms (P=0.04), paravalvular complications (P<0.01), prosthetic valve dehisence (P<0.01), and intracardiac abscess (P<0.01). The decision to pursue EVS was more common in patients with parvalvular complications, prosthetic valve dehiscence, or intracardiac abscess.

Overall, patients who underwent EVS had a lower unadjusted one-year mortality than patients who did not undergo EVS (34% vs. 59%, P<0.01). It is possible, however, that this is explained by the younger age and longer duration of symptoms (survivorship bias) in the group that underwent EVS. In the risk adjusted model, older age, stroke, and cardiac failure were all associated with a higher risk of both in-hospital mortality and one-year mortality, while EVS was not associated with a lower risk of either of these outcomes. Interestingly, though, the group that underwent EVS had a higher mortality within the first week following surgery, albeit not significant, and a significantly lower mortality on days 8 to 365. This suggests that patients who are good operative candidates (ie, those at lower risk for immediate post-operative mortality), do gain benefit from EVS for PVIE involving S. aureus. Determining this lower risk group, however, remains the clinical challenge.

Michael Calderwood, MD
Assistant professor of medicine, Harvard Medical School
Assistant hospital epidemiologist, Brigham and Women’s Hospital

Disclosure: Calderwood reports no relevant disclosures.