Percutaneous Coronary Interventions (PCI): Perioperative Antithrombotic Therapy and the Anesthesia Provider in 200

Paul M Kempen, MD, PhD

Letter to the Editor

The recent article in the APSF Newsletter regarding the perioperative management of patients with drug-eluting stents is timely, informative, and should be required reading for contemporary anesthesia practitioners.1 Stenting with drug-eluting stents (DES) has become the most commonplace method of treating occlusive coronary disease, with 1 million stents placed each year. The Science Advisory in the editor’s note is of special importance, advocating postponement of elective surgery for at least 1 year after DES placement, if possible, and emphasizes the acute need for very critical review of routine orders to hold aspirin or clopidogrel prior to surgery.2 Such “routine policies” are misguided, as perioperative antithrombotic therapy should involve a comprehensive risk/benefit analysis regarding surgical bleeding vs. stent thrombosis, whereby the latter will typically remain the primary concern. The presented proposed strategy used at Wake Forest clearly emphasizes the dangers and complexities associated with effective perioperative management of patients presenting after coronary stent placement. It does provide one paradigm of antithrombotic management: continued aspirin therapy and bridging infusion of GP IIb/IIIa Inhibitors (GPI) and heparin. The Science Advisory itself indicates, however, that there are no data to date to support this GPI bridging therapy practice. This “Wake Forest Protocol (WFP),” like other published recommendations, leaves many additional and extremely pragmatic questions unanswered.2-6 Answers to these important questions are also unlikely to become “evidenced based,” any time soon.

Pertinent questions remain: should surgical procedures in patients with coronary stents be undertaken only in tertiary centers with active interventional cardiology (>400 PCI/year as recommended by 2005 AHA/ACC guidelines7) and open heart programs with 24-hour availability (e.g., like Wake Forest)? How soon after surgery will repeat PCI be possible in the event of stent thrombosis in any given patient? Should patients for urgent surgeries be referred for management recommendations regarding percutaneous transluminal coronary angioplasty (PTCA)/bare metal vs. DES treatment to shorten intervals of mandatory antiplatelet therapy, if found in need of preoperative PCI? What procedures are associated with such excessive risk for surgical bleeding as to truly require discontinuation of thienopyridine? Further, should aspirin ever be discontinued (i.e., neurosurgical procedures)? What should be done with a patient with drug-eluting stents (DES) who presents for surgery after inappropriately discontinuing aspirin and thienopyridine therapy for several days in anticipation of surgery? Should these patients undergo repeat stress testing prior to surgery? After what interval should antiplatelet therapy be reinstituted? How long after DES placement should repeat stress testing occur? Does “patient compliance” affect this decision, and how can compliance be monitored? Should the cardiologist who placed the stent be personally involved in all perioperative agreements “between cardiology and surgery” as proposed in the WFP? What should occur in the event of disagreements? Why is “anesthesiology” not involved in the decision process, i.e., the perioperative physician? Should ALL stented patients undergo preoperative screening a week before scheduled surgery by an anesthesiologist in the pre-admission testing clinics to insure this complex coordinated care and eliminate “production pressures”? Surgeons will always fear bleeding. Production pressures are poorly combated in the holding area. How long after stent placement should this/any degree of concern persist and require strict assessments? What should be done if GPI or heparin allergy (i.e., heparin-induced thrombocytopenia) makes the WFP impractical and how is the “bridging therapy” optimally monitored and transitioned?

Aspirin and clopidogrel have elimination half-lives of 2-3 and 7.5 hours, respectively, while drug-exposed platelets are typically irreversibly affected, causing platelet inhibition until new, unaffected thrombocytes are produced.8,9 It is likely that perioperative administration of a titrated platelet infusion would typically correct drug-induced thrombasthenia caused by these agents, if antiplatelet drugs are last administered the morning prior to surgery and reduced to very low blood levels. While ABO identical or compatible units are preferred for transfusion, they are not required. In adults, ABO incompatible platelets may be used because the volume of plasma in the product is usually not clinically significant. Apheresis units may contain 350 mL of plasma, but passive transfer of antibodies rarely results in hemolysis.10 Thus, selective use of apheresis platelets in surgical patients from directed (i.e., spouse?) or proven repeat donor sources (repeatedly tested to further minimize infectious risks) may prove to be a viable alternative in elective patients who do not discontinue dual therapy prior to surgery and then actively display a need for functional platelets intraoperatively. An approach of this sort is not significantly different from autologous donation programs. This approach could allow for prospective intraoperative examination of bleeding tendency and “need to treat” for individual surgical procedures. It may also maximize stent-protective perioperative antiplatelet therapy, especially if these patients are placed as first cases of the day. The role of platelet function testing is evolving as well. Clearly, emergent surgeries will continue to present, where antiplatelet therapy is addressed with random donor platelets. An apheresis program of this sort may lead to increased availability of apheresis platelet transfusions overall and specifically in emergent cases.

Guidelines from anesthesia specialists in France, Britain, and Canada provide additional useful information for rational decisions from the viewpoint of the member anesthesiology specialists, but are often discounted by surgical colleagues as “foreign.”3-5 Unfortunately, there has been no attempt to develop such national guidelines by the American anesthesiology societies, and I would hope the APSF might champion this needed task, perhaps by first endorsing the Canadian Guideline and then via consensus development. This would offer opportunity to consider the multiplicity of perioperative eventualities, as well as educating and promoting needed specialty awareness to this very real and specific danger. Published recommendations from the conglomerate efforts of American non-anesthesiology specialists have left many anesthesia-specific questions unanswered.1,2,6

Often, production pressures overwhelm anesthesiologists and CRNAs when (institutional routine and) surgeons terminate antithrombotics inappropriately and push to do elective procedures.11 The lack of clear and timely anesthesia specialty guidelines in the USA stands in stark contrast to other advanced countries.3-5 We, as the definitive “perioperative specialists” cannot fail to issue such practice-specific and important guidelines to underscore safe specialty practice, where controversy abounds and the dangers are real. Without specialty guidelines, we must, as individuals, continue to sort out and individually defend patient safety with logic alone, and often clearly without “evidenced-based proof.” Personal experience repeatedly teaches that sudden cancellation of surgeries in recently stented patients based on “cutting edge knowledge” is often difficult, time consuming, and fraught with surgical
and administrative animosity. Such difficulty mounts, especially when faced with “cleared for surgery” written on a prescription pad of a third-party internist or non-interventional cardiologist, consulted specifically to “clear for surgery.” Furthermore, the importance of involvement of the stenting cardiologist and possibly hematologist appears paramount (and equally impossible when faced with a patient for a 7:00 am surgical start), given the complex and needed (and as yet inadequately defined by outcome-based research) perioperative care, risk assessment, and the multiplicity of factors involved in stent thrombosis: All stents are not equal and not all cardiologists place stents! Problems are best anticipated and avoided, not solved. The APSF may be the best venue to address this issue at this time.

Paul M Kempen, MD, PhD
Pittsburgh, PA

References

  1. Newsome LT, Kutscher MA, Gandi SK et al. A protocol for the perioperative management of patients with drug eluting stents. APSF Newsletter Spring 2007; 21(4):81-2.
  2. Grines CL, et al. Prevention of premature discontinuation of dual antiplatelet therapy in patients with coronary artery stents: A science advisory from the American Heart Association, American College of Cardiology, Society for Cardiovascular Angiography and Interventions, American College of Surgeons, and American Dental Association, with representation from the American College of Physicians. Circulation 2007;115:813-18.
  3. Vicenzi MN, Meislitzer T, Heitzinger B, et al. Coronary artery stenting and non-cardiac surgery—a prospective outcome study. Br J Anaesth 2006;96:686-93.
  4. Dalal AR, D’Souza S, Shulman MS. Brief review: Coronary drug-eluting stents and anesthesia: [Article de synthese court : Les tuteurs coronariens actifs et lanesthesie]. Can J Anaesth 2006;53:1230-43.
  5. Vichova Z, Albaladejo P, Marret E, et al. [Coronary stents and anaesthesia: it is time to have national data.] Ann Fr Anesth Reanim 2007;26:157-60. Epub 2006 Dec 22.
  6. Weitz HH. How soon can a patient undergo noncardiac surgery after receiving a drug-eluting stent? Cleve Clin J Med 2005;9:818-20
  7. Smith SC, et al. ACC/AHA/SCAI 2005 guideline update for percutaneous coronary intervention: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation 2006;113:e166-286.
  8. Benedek IH, Joshi AS, Pieniaszek HJ, et al. Variability in the pharmacokinetics and pharmacodynamics of low dose aspirin in healthy male volunteers J Clin Pharmacol 1995;35:1181-6.
  9. Caplain H, Donat F, Gaud C, Necciari J. Phamacokinetics of clopidogrel. Semin Thromb Hemost. 1999;25(Suppl 2):25-8.
  10. Lyons V, Triulzi DJ. Platelet transfusion therapy. Pittsburgh, PA: Institute for Transfusion Medicine; 1999. Available at http://www.itxm.org/tmu1998/tmu9-99.htm. Accessed April 28, 2007.
  11. Hedderich RL. National support needed to fight production pressures. APSF Newsletter 2006;21(3):55.