Printer-friendly format

The advent of coronary stenting as a primary revascularization option over the past decade has created management challenges for cardiologists, surgical subspecialists, anesthesiologists, and primary care physicians alike. Significant among these has been the problematic selection of specific therapeutic approach and device selection in patients with coronary artery disease, and the management of subsequent requisite antiplatelet therapy in those with implanted stents in the perioperative period for those patients who require elective or urgent non-cardiac surgical procedures. Percutaneous coronary interventions (PCI) now numerically supercede coronary artery bypass surgeries each year, and stents are favored over conventional balloon angioplasty as a result of enhanced procedural success and diminished restenosis rates. Avoiding the severe complication of stent thrombosis (ST) after implantation requires strict adherence to dual antiplatelet regimens including both thienopyridines such as clopidogrel along with concomitant aspirin (ASA). Both bare metal stents (BMS) and drug eluting stents (DES) are at risk for catastrophic thrombotic occlusion with dire results if these agents are inadvertently or prematurely discontinued, and the pro-thrombotic state that exists immediately following surgery, especially if general rather than regional anesthesia is utilized, puts this patient population at particular risk. The number of non-cardiologist physicians involved in the decision-making as to necessity, safety and timing of noncardiac surgical procedures increase the likelihood that mistakes may be made with the potential for ST to occur.

The mortality rate of ST, particularly in the post-operative patient, has been estimated on the basis of limited data from relatively small studies to be as high as 25-50%, and potentially as high as 75%. The risk of occurrence likely extends beyond two weeks following stent implantation, and probably for six weeks, for all stents. The reduced restenosis rate for DES over BMS is directly related to inhibited re-endothelialization of exposed stent struts, and the risk period for ST is therefore greatly prolonged for DES, whether sirolimus coated (SES) or paclitaxel coated (PES). There is data confirming that this risk extends to ninety days for SES and six months for PES, and experience has suggested that there is likely significant risk for ST for a full year, and perhaps beyond. In the future, bioresorbable stents or antibody-coated stents that can attract endothelial progenitor cells may be available and minimize the risk of perioperative ST, but for the time being clinicians from multiple disciplines must make management decisions within the constraints of the available technology.

Several approaches to prevention of perioperative ST are apparent. Many patients with coronary disease requiring noncardiac surgery may not necessarily benefit from preoperative revascularization, and can be safely managed medically with adequate perioperative beta blockers and careful attention to hemodynamics and blood loss during the planned procedure. Obviously, patients with severe left main disease, critical obstruction of major epicardial vessels, and acute coronary syndromes would not be included in this category. Nonetheless, the first question the clinician should ask is whether the patient actually needs preoperative revascularization. If the answer is yes, the next bifurcation in the management algorithm is to assess whether conventional balloon angioplasty without stent implantation is feasible, particularly if a good angiographic result is expected, or whether surgical revascularization with coronary artery bypass may provide the safest overall option for the given situation under consideration. If the anticipated noncardiac surgery will need to transpire in less than six weeks, these may represent the best options. Stenting can sometimes not be avoided, either because of suboptimal angioplasty results or lesion complexity. If the anticipated noncardiac surgery needs to transpire in a time frame of less than twelve months, BMS implantation is likely preferable to DES, given the greater rapidity of endothelialization with the former. If surgery can be delayed greater twelve months, then selection of DES may not be inappropriate, although reports of delayed late and very late ST beyond twelve months have been recently reported, and are of some concern.

Other strategies to avoid ST in the stented patient undergoing surgery would include consideration of continuing dual antiplatelet therapy throughout the perioperative time frame. For many minor procedures this may well be reasonable, such as dental extractions, cataract surgery, and dermatologic procedures; this strategy is obviously not appropriate for patients in whom excessive bleeding would have potentially dire consequences is in the case of most neurosurgery patients. Consideration to stopping clopidogrel and "bridging" the patient with a shorter acting antiplatelet agent such as IIb/IIIa inhibitors may have some rationale, but is logistically difficult and expensive, and there is currently no evidence-based data to confirm this approach as efficacious. When the decision is made to briefly interrupt dual antiplatelet therapy for unavoidable situations, minimizing the time period of discontinuation of clopidogrel, continuation of ASA if at all feasible, and early reloading of clopidogrel with a 600 mg loading dose may minimize risk of ST.

The importance of continuing education of all involved in the decision-making, including primary care physicians, surgical subspecialists, cardiologists, and the patients themselves, will be paramount in minimizing the incidence of perioperative coronary stent thrombosis. Important issues in addressing a given case will remain determining the date and type of stent implantation, consultation among all of the practitioners involved including the patient's cardiologist, arriving at the safest treatment stratagem for the specific situation, and performance of the planned surgical procedure in a center with the capability of immediate PCI in the unfortunate event that ST occurs.

References

Brilakis ES, Banerjee S, Berger PB. Perioperative Management of Patients with Coronary Stents. J Am Coll Card, 49:2145-2150, 2007.
Grines CL, Bonow RO, et al. Prevention of Premature Discontiuation of Dual Antiplatelet Therapy in Patients with Coronary Stents; AHA/ACC/SCAI/ACS/ADA Science Advisory. Circ 115:813-818, 2007.

Presented in Partnership by Nashville Medical News and Vanderbilt University Medical Center

Tags:

None

Login and voice your opinion!