Heart device infection rates low for both antibiotic regimens in randomized trial
A trial designed to test the effectiveness of additional antibiotic prophylaxis before and after cardiac electronic device implantation found that such an approach did not significantly lower the rate of subsequent infections, although there was a trend in that direction.
Researchers led by Andrew D. Krahn, MD, performed a cluster randomized trial of 19,603 patients with procedures related to cardiac implantable electronic devices (CIEDs), including 12,842 who were deemed high risk due either because they were repeat procedures on an existing pocket or related to cardiac resynchronization therapy devices. Low-risk procedures were typically new implants for pacemakers or implantable cardioverter-defibrillators.
Each institution was randomly assigned to either conventional or incremental antibiotic treatment protocols during four six-month periods, with a randomized reassigning of the regimens after each period. The conventional treatment, which is supported by guidelines, involved one pre-procedural infusion of cefazolin. The incremental treatment included that same infusion plus pre-procedural voncomycin, intraprocedural bacitracin pocket wash and two days of oral cephalexin following the procedure.
Overall, 1.03 percent of patients in the conventional treatment group were hospitalized for device infection within one year, compared to 0.78 percent of those treated more intensively with antibiotics. Among high-risk patients, the device infection rates requiring hospitalization were 1.23 percent and 1.01 percent for the conventional treatment and incremental treatment groups, respectively.
“Although there was no significant reduction in the rate of hospitalization for infection with this policy, we observed a modest trend in favor of this approach,” wrote Krahn, with the University of British Columbia in Vancouver, and colleagues in the Journal of the American College of Cardiology. “The ability of the study to demonstrate a statistical difference was limited by a rate of device infection in the conventional treatment arm that was 40% lower than previously reported; and by a more modest observed effect than hypothesized.”
Indeed, the authors noted that CIED infections had previously been estimated to occur in about 2 percent of all cases, with the risk lying somewhere between 2 and 4 percent in high-risk patients.
“The treatment cost of device infection is high, with case costs of $146,000 attributed to hospitalization, long courses of intravenous (IV) antibiotics and frequent need for system removal,” they wrote. “Prevention of infection is a major concern for device implant centers, which use standard policies to optimize outcomes.”
But this trial failed to show a significant benefit for the more intensive antibiotic regimen, and there were no meaningful differences between groups in terms of the etiology of the infections or the proportion of them that were polymicrobial.
The study population was 72 years old on average, with one-third of patients being female and 40 percent of them having a history of heart failure. Krahn et al. said the study cohort itself was unlikely to explain the lower-than-expected infection rates because they included all patients treated at each of the 28 participating centers.
However, “there may have been a ‘Hawthorne’ effect,” the researchers noted, “insofar as being in a research study led centers to increase vigilance to both antibiotic adherence and surgical technique to minimize infection rate. A nonsignificant trend of reduction in infection rate over time was seen in both arms of the study, consistent with a health system intervention effect.”
Considering the low infection rates of this study, the authors calculated a 20 percent reduction in infections with incremental antibiotics would only prevent one infection for every 500 patients treated—“a number that may be of questionable value unless the absolute risk exceeds some level warranting the intervention.”
“Further work is necessary to determine the potential characteristics of those patients that may benefit from this or any incremental intervention, including the WRAP-IT (World-wide Randomized Antibiotic Envelope Infection Prevention Trial) evaluating the incremental benefit of an antibiotic-impregnated envelope in high-risk CIED patients,” they wrote.
Daniel joined TriMed’s Chicago editorial team in 2017 as a Cardiovascular Business writer. He previously worked as a writer for daily newspapers in North Dakota and Indiana.