Eligible studies were randomised controlled trials (RCT), case-control or cohort studies that compared the safety and efficacy of uninterrupted warfarin therapy to heparin-based bridging in patients who underwent pacemaker or implantable cardioverter-defibrillator implantation. Outcomes of interest were bleeding and thromboembolic events. Only studies published in peer-reviewed journals were eligible.
Type of heparin used were unfractionated or low molecular weight. Timing of heparin administration ranged from six hours to 24 hours. Pre-operative INR (international normalised ratio) ranged from 2.0 to 2.6 for uninterrupted warfarin and 1.1 to 1.5 for heparin-based bridging. Most patients were also taking aspirin before operation. In the included studies, the clinical indications for warfarinisation were atrial fibrillation, cerebral vascular accident, deep vein thrombosis, pulmonary embolism and transient ischaemic attack.
Type of procedures performed were generator changes, permanent pacemaker, implantable cardioverter defibrillator and cardiac resynchronisation devices, where reported. Operator experience varied across the studies.
Two reviewers independently performed the study selection. Any disagreements were resolved by a third reviewer.