For patients undergoing pacemaker or defibrillator implantation, the continuation of warfarin (Coumadin, Bristol Myers-Squibb) with an international normalized ratio (INR) is safe and can reduce incidence of complications, according to a study published in the June edition of the Heart Rhythm Journal.
“Current guidelines recommend stopping oral anticoagulation and starting bridging anticoagulation with intravenous heparin or subcutaneous enoxaparin when implanting a pacemaker or defibrillator in patients at moderate or high risk for thromboembolic events,” the authors wrote.
Imdad Ahmend, MD, of the Regions Hospital in St. Paul, Minn., and colleagues assessed the safety of 459 anticoagulated patients who underwent device implant surgery without the cessation of warfarin between April 2004 and September 2008.
Patients were split into three groups. The researchers continued warfarin during the perioperative period in 222 patients. Additionally, the researchers held warfarin and administered bridging therapy—66 percent subcutaneous enoxaparin (Lovenox, Sanofi-Aventis) and 34 percent on intravenous heparin—in 123 patients and 114 patients had warfarin stopped without receiving bridging therapy.
While the researchers said that bridging therapy helps to minimize the time before and after device implant when anticoagulation is subtherapeutic, they said that bridging therapy often leads to a higher risk of pocket hematomas or other bleeding complications.
“Although the period of subtherapeutic anticoagulation is short, it could expose patients to potential thromboembolic complications,” the authors said.
According to the results, 10 patients—one in the continued warfarin group, seven in the bridging group and two in the anticoagulation-withheld group—had pocket hematomas.
The researchers found that there was a 16-fold increase in the incidence rate of pocket hematomas in the bridging therapy group compared to those on continued warfarin.
The results also showed that transient ischemic attack (TIA) occurred in five patients three days after surgery: four patients in the anticoagulation-withheld group and one patient in the bridging therapy cohort.
While length of hospital stay was similar in both the continued warfarin and anticoagulation-withheld patient arms, those in the bridging therapy arm had increased length of stay: 1.23 days compared to 2.27 days, respectively.
While “bridging therapy was associated with a higher incidence of bleeding complications and a longer hospital stay,” the authors wrote, “patients in whom anticoagulation was withheld had a higher risk of TIAs.”
The authors said that the longer lengths of stay for patients on bridging therapy was due to the fact that those on intravenous heparin must be hospitalized until the INR reaches therapeutic range.
While the authors said that more prospective, randomized clinical trials are still needed to confirm these findings, “continued warfarin therapy with therapeutic INR appears to be safe and cost effective compared to bridging therapy or temporarily withholding of anticoagulation.”