Continuation of Warfarin During Pacemaker or Implantable Cardioverter-Defibrillator Implantation: A Randomized Clinical Trial

Study Questions:

How safe is pacemaker or implantable cardioverter-defibrillator (ICD) implantation in the presence of a therapeutic international normalized ratio (INR)?


One hundred anticoagulated patients (mean age 71 years) referred for pacemaker/ICD implantation were randomly assigned to warfarin continuation (n = 50) or warfarin discontinuation (n = 50) with the option of heparin bridging (n = 7). The primary endpoint was a composite of thromboembolic and hemorrhagic events, warfarin-induced skin necrosis, and heparin-induced thrombocytopenia.


The mean INR during the procedure was 2.2 in the warfarin-continuation group and 1.3 in the warfarin-interrupted group. There was a trend toward a lower prevalence of the composite endpoint in the warfarin-continuation group (0%) than in the warfarin-interrupted group (10%), but the difference was not statistically significant.


In anticoagulated patients, warfarin continuation during device implantation may be preferable to interruption of warfarin.


Prior studies have shown that bleeding complications are more common with heparin than warfarin in patients undergoing device implantation. Therefore, in a comparison of warfarin-continuation versus warfarin-interruption, the routine use of heparin-bridging would maximize the probability of finding an advantage of warfarin continuation over warfarin interruption. One reason this study did not demonstrate a significant difference in outcomes between the two strategies is that only 7/50 patients in the warfarin-interrupted group were bridged with heparin. Another reason is that the study was underpowered to detect a significant difference between the two strategies.

Clinical Topics: Anticoagulation Management, Arrhythmias and Clinical EP, Implantable Devices, SCD/Ventricular Arrhythmias

Keywords: Blood Coagulation, Warfarin, Heparin, Pacemaker, Artificial, Defibrillators, Implantable, Thrombocytopenia

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