Perioperative management of surgical patients who require temporary discontinuation of vitamin K antagonists (warfarin) or antiplatelet drugs is complicated. The risk of a thrombotic event during interruption of anticoagulant or antiplatelet therapy must be weighed against the risk of bleeding when such therapy is used in close proximity to a surgical procedure. This balancing of risks is guided by the patient’s individual risk for thromboembolism or bleeding and underlying conditions such as the presence of a mechanical heart valve or a coronary stent.
High-profile adverse events have made anticoagulant and antiplatelet management one of the most highly litigated aspects of perioperative medicine. Moreover, there is a paucity of randomized clinical trial data and definitive guidelines to address the perioperative needs of patients on antithrombotic therapy. Treatment protocols vary depending on many underlying factors, such as the presence of mechanical heart valves, comorbidities, stent type and location, patient age and medical history, and type of surgical procedure. While recent attention has focused on genetic variations that result in higher or lower sensitivity to warfarin in some patients, routine genetic testing for warfarin sensitivity is controversial and not part of widespread practice at this time.
The first portion of this article explores key issues and principles in the perioperative management of surgical patients on warfarin therapy, and the second portion does the same for surgical patients on antiplatelet therapy.
ACCP RECOMMENDATIONS FOR PERIOPERATIVE ANTICOAGULANT MANAGEMENT
Patients with mechanical valves who are at high risk for perioperative thromboembolism include those with any mechanical mitral valve, an older valve, or a history of stroke or transient ischemic attack (TIA). Patients with atrial fibrillation who are at high risk include those with a recent stroke or TIA, rheumatic valvular heart disease, or a CHADS 2 score of 5 or 6. (The CHADS 2 scoring system assigns one point each for a history of congestive heart failure, hypertension, age greater than 75 years, or diabetes, and two points for history of stroke or TIA.) Patients with a history of VTE within the prior 3 months are also considered high risk.
Bridging anticoagulation (bridge therapy)—ie, the temporary use of intravenous unfractionated heparin (IV UFH) or low-molecular-weight heparin (LMWH) prior to surgery—is central to the ACCP’s recommendations for perioperative management in patients on long-term anticoagulant therapy. Key ACCP recommendations 1 for these patients, according to their risk for thromboembolism ( Table 1 ), are as follows:
- High risk —bridging anticoagulation with therapeutic-dose subcutaneous LMWH or IV UFH
- Moderate risk —bridging anticoagulation with therapeutic-dose subcutaneous LMWH, therapeutic-dose IV UFH, or low-dose subcutaneous LMWH
- Low risk —bridging anticoagulation with low-dose subcutaneous LMWH or no bridging.