Alternative antibiotic strategy modestly improves cardiac device infection rate
BOSTON — A novel antibiotic strategy lowered the infection rate in patients undergoing surgery related to implantable cardiac devices, but the difference compared with the usual care IV cefazolin alone was not significant, according to new data from the PADIT trial.
The alternative antibiotic strategy consisted of a single preoperative dose of IV cefazolin and vancomycin, an intraoperative bacitracin pocket wash and oral cephalosporin for 2 days after cardiac device surgery.
Currently, the only guideline recommendation to prevent such infections is administration of IV cefazolin, but methicillin-resistant gram-positive microorganisms do not respond to cefazolin, Andrew D. Krahn, MD, FHRS, head of the division of cardiology at the University of British Columbia in Vancouver, said during a presentation at the Heart Rhythm Society Annual Scientific Sessions.
When these patients get infections, “they undergo risky invasive procedures, end up having to have the device removed, and need a long course of antibiotics and then surgery afterwards to implant the new device,” Krahn said during a press conference. “This occurs in 2% of patients. When something catastrophic happens to 2% of patients, you need a very large-scale study to address that question.”
The PADIT study was conducted to assess whether an incremental regimen of perioperative antibiotics would reduce device-related infections compared with IV cefazolin. Krahn and colleagues randomly assigned 28 centers in Canada and the Netherlands to administer the incremental regimen or IV cefazolin to 19,603 patients undergoing cardiac device procedures (mean age, 72 years; 34% women). Each site crossed over to the other strategy after 6 months. At 12 months, the sites were re-randomized, and then crossed over to the other strategy at 18 months.
All centers included high-risk patients, defined as those who had a repeat procedure in the arrhythmia device pocket such as a generator change, a lead or pocket procedure or an upgrade; or those implanted with a cardiac resynchronization therapy device. Six centers also included low-risk patients, defined as those who had a pacemaker or implantable cardioverter defibrillator implanted for the first time.
The primary outcome was hospitalization attributed to device infection. Patients were followed for 1 year after the 2-year enrollment period. The trial was designed with a projected infection rate of 2% per year, and the primary analysis included the high-risk patients, Krahn said.
According to data reported at the HRS Scientific Sessions, the primary outcome was modestly lower in the incremental group (0.78% vs. 1.03%; OR = 0.77; 95% CI, 0.56-1.05).
“The infection rates we expected to be about 2% were 1%,” Krahn said at the press conference. “The [incremental strategy] reduced the rate of infection by about 20%, but did not achieve statistical significance.”
The results were consistent across subgroups. “I interpret that as there is a modest effect, but it was too small for this kind of study to detect that effect and find it significant,” Krahn said. “We were seeking a definitive result that would have established this treatment as mandatory. That did not take place. I believe providers will look for the patients they believe to be at highest risk, and consider the incremental investment for them.”
Adverse events were low and similar between the groups aside from allergic reactions, which were higher in the incremental group (0.2% vs. 0.1%; P = .018).
“The downsides to doing [the incremental strategy] were pretty trivial,” Krahn said.
The lower-than-expected infection rate “may reflect the Hawthorne Effect: If you measure and tell people you’re watching, that creates a fastidious culture of attention to detail,” he said. – by Erik Swain
Krahn AD, et al. LBCT01-01. Presented at: Heart Rhythm Society Annual Scientific Sessions; May 9-12, 2018; Boston.
Disclosure: Krahn reports he received research grants from Boston Scientific and Medtronic and compensation for services from Medtronic.