Beware Valve Involvement in Device-Related Infective Endocarditis

April 30, 2012

April 27, 2012 (Boston, Massachusetts) — The outlook for survival is significantly better if a pacemaker or other implantable device associated with infective endocarditis is explanted, especially if there is tricuspid-valve involvement, confirms an observational study primarily of pacemaker-associated endocarditis [1].

Especially with valve involvement, removing the pulse generator and leads can significantly improve the otherwise-high associated one-year mortality, according to the analysis of 177 cases of device-related endocarditis out of a 2760-patient cohort of infective endocarditis from any cause.

The cases come from a total of >3000 patients from 28 countries prospectively enrolled from 2000 to 2006 in the International Collaboration on Endocarditis-Prospective Cohort Study (ICE-PCS).

Although removing the involved pulse generator and leads is the standard of care in such cases, device removal wasn't done in some patients in the series, largely because of "host factors" that collectively point to their being especially sick or fragile and who may therefore have been considered at too high risk for explantation surgery, senior author Dr Andrew Wang (Duke University Medical Center, Durham, NC) told heartwire .

The study was published in the April 25, 2012 issue of the Journal of the American Medical Association, with lead author Dr Eugene Athan (Barwon Health, Geelong, Australia).

After one year, 19.9% of the 141 patients in whom the device was removed at the index hospitalization had died, vs 32.8% of those in whom the device was left in place (mortality hazard ratio [HR] for device removal 0.42; 95% CI 0.22–0.82).

About 37% of patients had coexisting valve infection; 43 of the 66 cases involved the tricuspid valve. The HR for in-hospital mortality associated with device-related endocarditis with valvular involvement was 2.75 (95% CI 1.30–5.83).

"Although there have been previous studies describing the short-term outcome and treatment of this condition, in this study--although there are limitations with regard to why some patients didn't have device removal--we did find there was a survival benefit to device removal, which I think has been always assumed but not previously shown," according to Wang.

Another important finding, he said, "is the high association of cardiac device infection with valve infection. That complication, which was quite common, was another factor associated with worse outcome, really independently of whether the device was removed."

Device-related endocarditis was related to healthcare-system–associated infection in 45.8% of cases; they included hospital-acquired infections (about two-thirds) and those arising prior to hospitalization but after "extensive out-of-hospital contact with healthcare interventions" (about one-third).

The in-hospital mortality in such healthcare-related endocarditis involving devices, about half the time caused by Staphylococcus aureus (a third of those were methicillin-resistant), was 22.2%.

"I think the whole description of infection as healthcare associated is really almost a composite end point of factors related to the host as well as the type of organism," Wang said. It tends to represent patients "who generally have a lot of other medical problems, are exposed to healthcare a great deal, and who likely have a poor outcome just from those factors."

Overall, the findings suggest that the risk associated with leaving the device in is more serious than often appreciated, so even if the patient is very sick or fragile, "I think you'd have to have a very strong reason to think you could treat through it, as opposed to removing it."

Wang acknowledges that the contemporary impact of implantable device types on such device-related endocarditis will require further study. The current analysis doesn't reflect the much higher modern prevalence of implantable defibrillators and biventricular pacemakers, both of which involve more leads and higher procedural risk than traditional pacemakers from the last decade.

Although the need for a defibrillator or biventricular pacemaker would also track with poorer clinical status, "I think experience is growing with regard to extraction, and within the past several years there's a growing confidence that the devices can be safely extracted." he said. "Whereas before, I think there was an appropriate concern about bad complications with device removal."

Athan had no disclosures. Wang reports providing expert testimony for trial defense; receiving grants or having grants pending from Gilead Sciences, Edwards Lifesciences, and Abbott Vascular; receiving payment for lectures from American Physician; receiving royalties for serving as an editor from Springer; and receiving payment for development of educational presentations from the American College of Cardiology Foundation. Disclosures for the coauthors are listed in the paper.