With surgery and introduction of a foreign object into a patient always comes some risk of infection. However, according to a study published online July 31 in Circulation, reducing that risk may involve more than just a clean site.

Other recent surgeries, including peri-implant surgical complications, recent valve implants, the need to re-enter to adjust leads and to change recalled devices are some of the factors that researchers found increased risk in patients.

Jordan M. Prutkin, MD, MHS, of the University of Washington in Seattle, and colleagues reviewed 200,909 patients enrolled in the Medicare Implantable Cardioverter-Defibrillator (ICD) Registry between 2006 and 2009, with the intent to monitor trends in infection. Over the course of six months following surgery, 1.7 percent of patients developed infections. Researchers noted that patients who developed infections were fragile due to already poor health status and comorbid conditions.

Particular devices were also more likely than others to develop infections. Prutkin et al noted that 2 percent of cardiac resynchronization therapy (CRT)-ICD patients developed infections, more than single or dual chamber devices (1.4 percent and 1.5 percent, respectively), regardless of how leads were placed or introduced. Patients who were undergoing a device upgrade or battery change experienced 1.9 percent rate of infection.

Prutkin et al noted that ICD infection occurred far more frequently following an adverse event at the time of the recent procedure, 5.4 percent as opposed to 1.9 percent in patients who had no adverse events during surgery. Infections led to a nearly double six-month mortality rate in implanted patients.

Only battery replacement seemed to have low risks for infection following the procedure.

These rates were consistent with prior studies.

The research team suggested that part of this increased risk for patients who have recently experienced surgery may be due to a delicate balance being shifted between the growth of bacteria and fungi in the pocket surrounding the device when reopened before the body can fully eliminate or cope with what it was hosting. They cited 42 percent presence of bacteria found in pockets in previous studies. Extra blood due to hematoma, warfarin or other damage may encourage overgrowth.

With costs of hospitalizations for implantable device infections averaging between $24,000 and $130,000 and length of stay between eight and 20 days, post- and peri-operative device infections cost hospitals and patients significantly.

Keeping this in mind, Prutkin et al recommended caution when re-entering the pocket for any reason, but particularly for upgrade, lead adjustment, recalled devices, malfunction or any other reason that would require reopening the incision before battery replacement would be required.