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Perioperative anticoagulation strategies for pacemakers or ICDs
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According to American Heart Association statistics, approximately 532,000 patients underwent procedures related to implantation of cardiac pacemakers or implantable cardiac defibrillators in 2006. Given other pre-existing conditions, a large number of these patients may also be administered oral anticoagulation with warfarin or another coumarin derivative. This necessitates appropriate management of anticoagulant therapy perioperatively to balance the risk for thromboembolism from the underlying disease process with the risk for bleeding complications (particularly the development of pocket hematomas) associated with the procedure. Although no formal guidelines exist, several available articles have examined possible management strategies for this patient population.
 Kristin Montarella |
 Rhonda Cooper-DeHoff |
A systematic review published in 2008 by Jamula and colleagues provides an overview of the two most prevalent management strategies. The first strategy is the cessation of oral anticoagulation and bridging with unfractionated heparin (UFH) or low–molecular-weight heparin (LMWH). The second strategy is the continuation of oral anticoagulation therapy. The results of several small trials that assessed each management strategy were reviewed. For patients assigned to bridging therapy, the results of three trials using UFH all showed higher rates of pocket hematoma in the patients assigned to UFH compared with patients who were not assigned to heparin bridging. UFH was restarted at times ranging from immediately to up to 24 hours post-procedure, and the rates of pocket hematoma development ranged from 12% to 29%. Only one report was included that discussed the use of LMWH. LMWH was restarted a minimum of 24 hours after the procedure. Although only 21 patients were included, no patients developed bleeding events during the follow-up period. The findings of four trials were included in the Jamula review. The trials were conducted to assess patients who continued with their oral anticoagulation regimen at the time of procedure. These findings reported a mean INR on the day of procedure ranging from 1.5 to 6.9. The rates of pocket hematoma or other bleeding ranged from 1.9% to 24%, with the 24% observed in one trial of 21 patients substantially higher than that observed in the other reviewed trials. When this outlier trial was excluded, the range for bleeding among the other three larger trials ranged from 1.9% to 6.6%. Although there were limitations to all of the included trials, the rate of pocket hematoma development was lower in those patients who continued with oral anticoagulation therapy compared with those who were administered heparin bridging. The underlying reasons for these differences were not clear.
Based upon the above findings, these researchers developed a practical guide to the management of perioperative anticoagulation in patients scheduled for pacemaker or ICD procedures. Assessment of individual patient risk for thromboembolism was a primary factor in determining the best treatment approach. High-risk patients should be considered for either bridging therapy or continuation of oral anticoagulation. The researchers recommended bridging therapy with LMWH resumed 48 to 72 hours after the procedure instead of UFH use. For those patients in whom oral anticoagulation is administered, the researchers recommended an INR <3.0 on the day of procedure with a range of 2.0 to 2.5 as a target. Moderate- to low-risk patients can be continued on reduced-dose oral anticoagulation, or oral therapy can be stopped with no bridge therapy given.
Results of a small, single-center trial were recently published by Tolosana and colleagues. The trial included 101 patients deemed at high risk for thromboembolic complications if anticoagulation therapy was stopped at the time of pacemaker or ICD placement. Patients were randomly assigned to one of two treatment groups: A) switch from oral anticoagulation to UFH four days before implantation, or B) continued treatment with acenocoumarol to reach an INR of 2 ± 0.3 on the day of procedure. The primary outcome was the development of pocket hematoma and/or thromboembolic events in the 45 days post-procedure. Event rates were similar between the heparin-treated group (7.8%) and the acenocoumarol-treated group (8.0%). In all cases of pocket hematoma, development occurred before discharge. There were no thromboembolic events in either treatment group.
There are no available data from large, prospective, randomized, controlled trials to firmly define which treatment approach is optimal for the perioperative anticoagulation of patients assigned to pacemakers or ICDs. All of the trials discussed have limitations and methodological issues that limit interpretation of the results. Based on the above references, it appears feasible to maintain patients at high risk for thromboembolic events assigned to oral anticoagulation at the time of procedure. If this treatment strategy is selected, it is probably prudent to assess the patient’s INR several days before and on the day of the procedure to avoid performing procedures on patients whose INR is >3.
Kristin Montarella, PharmD, BCPS, is an Associate Professor of Pharmacy Practice, Southwestern Oklahoma State University College of Pharmacy, and Clinical Specialist, Integris Southwest Medical Center, Oklahoma City, Okla.
Rhonda Cooper-DeHoff, PharmD, MS, is an Associate Professor, University of Florida College of Pharmacy, Gainesville, and Cardiology Today’s Pharmacology Consult column editor and a member of the CHD and Prevention section of the Cardiology Today Editorial Board.
For more information:
- Jamula E. J Thromb Haemost. 2008;6:1615-1621.
- Lloyd-Jones D. Circulation. 2010;121:e1-e170.
- Tolosana JM. Eur Heart J. 2009;30:1880-1884.