Patients requiring long term anticoagulation often undergo transition of their warfarin to heparin in anticipation of invasive surgical procedures such as pacemaker or ICD implantation. This may require inpatient hospitalization several days prior to and after the procedure, potentially increasing medical costs and patient inconvenience. Patients undergoing such a process are initiated on heparin while their INRs drift to normal levels. Immediately prior to surgery, heparin is discontinued and restarted several hours after the procedure. Unfortunately, this process has resulted in a high incidence of surgical wound hematomas and other bleeding complications often requiring longer periods of discontinued anticoagulation or repeat surgical exploration. Previous investigators have tried to reduce the incidence of wound hematomas by prolonging the time from surgical wound closure to the reinitiation of heparin. A small randomized trial demonstrated that there was no significant difference in the incidence of wound hematomas whether heparin was started 6 hours or 24 hours after surgery (J Am Coll Cardiology 2000;35:1915-8). This has led many investigators to perform pacemaker and ICD implantation without reversal of warfarin therapy. A recent retrospective observational study demonstrated that the incidence of wound hematomas in patients with an INR of 2.6 was no different than patients with an INR of 1.5 (PACE 2004;27:358-60). Furthermore, a more recent, larger retrospective observational study reported in abstract form at the recent Heart Rhythm Society Annual 2007 Scientific Meeting demonstrated that not only is performing pacemaker and ICD implantations safe without reversing warfarin anticoagulation, but the incidence of wound hematomas is significantly smaller as compared to the strategy of reversing warfarin and initiating periprocedural heparin.