Today, more patients are presenting for non-cardiac surgery (NCS) after recent placement of either Bare Metal (BMS) or Drug-eluting (DES) stents. Stent thrombosis is an infrequent but devastating complication after stent implantation. This complication accounts for up to a 60% acute myocardial infarction rate and up to a 45% mortality rate.¹ Some notable risk factors for stent thrombosis include the presence of bifurcation and small vessel lesions, suboptimal angiographic results, high-risk patients (i.e., diabetes mellitus and renal failure), and most importantly, cessation of dual antiplatelet therapy (i.e., aspirin and clopidogrel).² Non-cardiac surgery performed following recent stent placement poses an additional risk of thrombosis due to the inherent hypercoagulable state of surgery as well as the common practice of discontinuing antiplatelet therapy perioperatively. Most perioperative stent thromboses occur intra- or postoperatively, as opposed to the preoperative “drug free” period. Proposed reasons include the prothrombotic nature of surgery, the time needed to synthesize new “aspirin-free platelets,” the wash-out of thienopyridine, or a combination of all of the above.^2,3

Given the complexity of this newly recognized perioperative phenomenon, it is not surprising that one survey reported that 63% of Canadian anesthesiologists did not know the published guidelines regarding the timing of elective surgery following stent placement.⁴ Part of the reason for this lack of knowledge is the paucity of definitive data to guide physician perioperative decision-making. This review will focus on some of the issues facing healthcare practitioners including the recommended timing of elective NCS following stent placement, the perioperative management of antiplatelet therapy prior to elective NCS, and the perioperative management of antiplatelet therapy prior to urgent/emergent surgery.

In June 2008, the American College of Chest Physicians (ACCP) published guidelines related to this topic.⁵ The emerging consensus suggests that, when possible, surgery should be delayed for at least 1 week following percutaneous transluminal coronary angioplasty (PTCA) without stent placement, with the recommended delay being extended to at least 4-6 weeks for BMS and for at least 12 months following DES placement.^5,6 The difference in recommended waiting periods for BMS versus DES is due to the slower rate of endothelialization for DES. These guidelines also state that patients who undergo surgery within 6 weeks of BMS placement or within 1 year of DES placement should continue perioperative dual antiplatelet therapy (Class IC).^5,6 However, these guidelines are based on expert opinion, case series, and small retrospective studies.

Two recently published large retrospective analyses by Nuttall et al. and Rabbitts et al. support these recommendations.^7,8 They investigated the rates of major adverse cardiac events (MACE-defined by a composite of death, myocardial infarction, stent thrombosis, and repeat revascularization) in patients undergoing NCS following either BMS⁷ or DES⁸ placement. The authors found that MACE occurred in 10.5% of patients when surgery was performed within 30 days of BMS placement, but dropped to 3.8% and 2.8% when performed between 30 and 90 days, and >90 days after BMS, respectively.⁷ Non-cardiac surgery within 90 days of DES placement resulted in a 6.4% rate of MACE, but declined to rates comparable to BMS (3.3%) only when surgery was delayed for at least 1 year.⁸ Avoiding elective surgery during these vulnerable periods is the optimal way to mitigate this perioperative complication.

The risk of perioperative bleeding associated with antiplatelet therapy must be weighed against the catastrophic event of stent thrombosis from discontinuation of antiplatelet therapy. A review by Chassot et al. recommended that all patients continue aspirin throughout the perioperative period, except in cases where excess bleeding could have irreparable consequences (i.e., intracranial surgery).⁹ The authors further state that when feasible, patients should continue dual antiplatelet therapy perioperatively. Both recent retrospective studies by Nutall et al. and Rabbitts et al. reported that perioperative bleeding was not associated with perioperative antiplatelet therapy.^7,8 Therefore, many cardiologists endorse continuing dual antiplatelet therapy indefinitely, especially during low risk bleeding procedures.² For those patients who must undergo urgent or emergent high risk bleeding procedures, bridging therapies such as unfractionated heparin, low molecular weight heparin, direct thrombin inhibitors, or glycoprotein IIb/IIIa inhibitors have been proposed for utilization. Presently, there is a lack of evidence supporting bridging therapy, and, therefore, the ACCP guidelines echoed by the recent practice alert in Anesthesiology do not suggest its routine use.^5,6 If surgery must be performed in patients that must have their thienopyridine therapy interrupted, it is recommended that aspirin be continued and the thienopyridine be started as soon as possible after the procedure.⁶ Further studies need to be performed to investigate alternative therapies for reducing the risk of stent thrombosis in patients undergoing emergent high risk bleeding surgeries.

In the absence of universally accepted protocols for management of patients who present for NCS following recent stent placement, it is necessary for collaborative decision making to take place between the patient, internist, surgeon, anesthesiologist, and cardiologist. We strongly encourage this multidisciplinary discussion to include the type and timing of stent placed, the importance of the type of surgery being considered, the management of perioperative antiplatelet therapy, and the choice of facility at which to perform the surgery. If surgery needs to be performed in patients with recent stent placement, if possible, it should take place where a 24-hour interventional cardiologist is available, as emergent PCI remains the best treatment option.²

Acknowledgments

The authors wish to thank John G. T. Augoustides, MD, FASE, FAHA (University of Pennsylvania Medical Center, Philadelphia) for sharing his expert opinion on this matter.

Dr. Greenberg is an associate professor, Dr. Matten is an instructor, Dr. Murphy is an associate professor, and Dr. Vender is a professor, all at the Northwestern University Feinberg School of Medicine, NorthShore University Healthsystem, Evanston, IL.

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