Perioperative Anticoagulation and Antithrombotic Management
GENERAL PRINCIPLES
• Patients on chronic anticoagulation for AF, VTE, or mechanical heart valves often need to undergo procedures that pose risk of bleeding.
• The indication for anticoagulation and risk of interruption must be weighed against the risk of bleeding of the procedure (including possible neuraxial anesthesia).
TREATMENT
• Recommended management varies according to the indication for anticoagulation, medication used, and surgical bleeding risk.
• For patients being treated with vitamin K antagonists (VKA) such as warfarin:
î Low bleeding risk procedures permit continuation of oral anticoagulation through the perioperative period (e.g., minor dental and dermatologic procedures, cataract extraction, endoscopy without biopsy, arthrocentesis). Pacemaker and implantable cardioverter defibrillator (ICD) placement lead to less hematoma if anticoagulation is not interrupted.31
î Significant bleeding risk procedures require the anticoagulation to be discontinued.
■ Although the international normalized ratio (INR) at which surgery can be safely performed is subjective, an INR of intraoperatively can have adverse effects on the function of implanted cardiac devices.
• A variety of errors can occur, from resetting the device to inadvertent discharge of an ICD.
• Complications are rare but are more likely with abdominal and thoracic surgeries.
• The type of device (i.e., pacemaker or ICD) and manufacturer should be determined along with initial indication for placement and the patient's underlying rhythm. History and ECG review should suffice.
• The device should be interrogated within 3-6 months of a significant surgical procedure.
TREATMENT
• If the patient is pacemaker dependent, the device should be reprogrammed to an asynchronous mode (e.g., VOO, DOO) for the surgery.
• The application of a magnet will cause most pacemakers to revert to an asynchronous pacing mode; however, if this is the planned management, it should be tested preoperatively, especially in the pacemaker-dependent patient.
• It should be noted that the effect of a magnet on ICDs is typically different from the effect on pacemakers in that it affects the antitachycardia function but does not alter the pacing function of most models. If the pacing function of an ICD needs to be altered perioperatively, the device will need to be reprogrammed.
• The antitachycardia function of an ICD will typically need to be programmed off for surgical procedures in which electrocautery may cause interference with device function, leading to the potential for unintentional discharge. The effect of a magnet on this function is variable, so programming is the preferred management. Continuous monitoring for arrhythmia is essential during the period when this function is suspended.
• Postoperative interrogation may be necessary, particularly if the device settings were changed perioperatively or if the patient is pacemaker dependent.
• Consultation with an electrophysiologist is strongly recommended if there is any uncertainty regarding the perioperative management of a device.