Safety and efficacy of bridging with low molecular weight heparins: a systematic review and partial meta-analysis.

BACKGROUND Surgical interventions in patients on long term vitamin K antagonist (VKA) treatment create a dilemma; periprocedural interruption of anticoagulation raises the risk of thrombosis, while continuation raises the risk of bleeding. The anticoagulation- free interval is minimized by "bridging" with parenteral anticoagulants. The efficacy and safety of bridging with low molecular weight heparins (LMWH) has however not been unequivocally established. METHODS We performed an EMBASE and MEDLINE search for studies that compared bridging anticoagulation with continuation or cessation of VKA without bridging; with thromboembolism (TE) and bleeding as outcomes. We identified 878 articles and finally selected 17. Results of individual studies were pooled. RESULTS None of the included studies reported significant differences in incidence of TEs between the bridging group and the comparator group; 4 out of 13 studies reported zero TEs. Heparin was identified as a risk factor for bleeding in multivariable adjusted analyses in 3 studies on pacemaker/implantable cardioverter defibrillator (PM/ICD) surgery. In 5 studies (different types of surgery) with unadjusted analyses, bridging was compared to warfarin cessation: 3 studies reported null results for bleeding; 2 studies identified bridging as a risk factor. We pooled a subset of 6 studies regarding postoperative bleeding after PM/ICD surgery and found a relative risk (RR) of 3.03 (95% confidence interval (CI), 1.86-4.95) for bridging compared to continuation of VKA. CONCLUSIONS While the antithrombotic efficacy of bridging with LMWH has not been demonstrated, increased bleeding risk is observed in different types of surgery. PM/ICD surgery can be safely performed on continued VKA.