Coronary artery stents: implications for perioperative management

Educational Objectives

The goal of this program is to improve the perioperative management of adult patients with coronary stents. After hearing and assimilating this program, the clinician will be better able to:

1. Identify major risk factors for late stent thrombosis.

2. Recognize the risks associated with premature discontinuation of antiplatelet therapy, and their management.

3. Plan the perioperative management of patients with ­drug-eluting stents.

Summary

Epidemiology: 1 million percutaneous interventions performed in United States annually; 90% of patients receive stent (compared to 400,000 coronary artery bypass grafts); ≈5% of patients with stents require surgery within 1 yr of placement

Stent complications: 20% to 30% of patients with ­bare-metal stents develop restenosis and need reintervention; as process is slow, body develops collateral circulation; symptoms manifest mostly during exercise; acute symptoms relatively rare; ­drug-eluting stents (DES) deliver medication that prevents restenosis; ­second-generation DES associated with restenosis rate of 1% to 2%

Late stent thrombosis (LST): acute clot formation at level of coronary stent occurring 30 days after stent implantation; major complication associated with DES; angiographic incidence 0.7% to 3.1%; clinically manifested as myocardial infarction or death in 80% (however, as many patients die before reaching hospital, incidence assumed to be higher than reported); platelet activation major cause of acute thrombus formation; currently, no test for identifying ­high-risk patients

Clinical risk factors per American College of Cardiology (ACC) and American Heart Association (AHA): stent placement for acute coronary syndrome, low ejection fraction, diabetes, or renal failure; angiographic risk factors — in prospective observational study of 2200 patients (2005), premature discontinuation of dual antiplatelet therapy (DAPT) associated with hazard ratio (HR) of 90 for LST, compared to renal failure (HR of 6.5), diabetes (HR of 3.7), or low ejection fraction (HR of 1); LST less common in patients stable on aspirin monotherapy for long period before surgery, and rare if DAPT maintained

Veterans Affairs study: in patients placed on DAPT (aspirin and clopidogrel [Plavix]) after treatment for acute coronary syndrome, risk for major cardiac event highest in first 90 days after stopping clopidogrel (attributed to rebound hypercoagulability); clopidogrel — administered as prodrug and metabolized in gut; 85% metabolized to inactive form; 15% metabolized in liver by cytochrome P450 system; some patients resistant due to genetic polymorphisms in P450 enzymes

Clopidogrel alternatives: prasugrel (Effient) — also administered as prodrug, but unaffected by genetic polymorphisms; greater antiplatelet activity than clopidogrel; discontinue 5 to 7 days before surgery; ticagrelor (Brilinta) — administered as active drug; binds reversibly to platelets; greater antithrombotic activity than clopidogrel; 50% of platelet function recovered within 1 day of discontinuation

Prasugrel: associated with lower rates of nonfatal myocardial infarction, need for target vessel revascularization, and stent thrombosis than clopidogrel; however, prasugrel associated with higher rate of fatal bleeding; indications include high risk for stent thrombosis, or proven resistance to clopidogrel; prasugrel harmful to patients with previous history of stroke; not beneficial (or dose reduction indicated) for patients <60 kg body weight or <75 yr of age

Ticagrelor: similar in efficiency to prasugrel; 50% of platelet function recovered within 1 day of discontinuation; bleeding profile similar to that of clopidogrel (lower rates than prasugrel); probably better choice for perioperative period

Perioperative management of patients at risk for stent complications: postpone ­semi-elective surgery if patient has undergone percutaneous transluminal coronary angioplasty (PTCA) within ≤14 days, or if bare metal stent placed within ≤2 mo; guidelines suggest waiting ≥1 yr after placement of DES (remain vigilant for LST even after 1 yr)

Perioperative antiplatelet therapy management: team (ie, anesthesiologist, cardiologist, and surgeon) approach recommended for managing risks for bleeding and major cardiac events; assess patient’s risk for LST; risk relatively low if patient stable on aspirin monotherapy; risk associated with DES higher than with bare metal stent; consider time elapsed since stent placement and number and location of stents (risk rises with stent number); history of previous stent thrombosis (risk for recurrence high), and presence of other risk factors (eg, diabetes, low ejection fraction, or renal failure)

Secondary considerations: hemorrhagic risk; individual risk factors (comorbidities that affect coagulability); urgency of surgery; possibility of alternatives to surgery

Point-­of-care platelet function testing: no randomized data yet available supporting use in management of antiplatelet therapy

ACC/AHA guidelines: continue DAPT for 1 mo if patient has ­bare-metal stent, 1 yr if patient has DES; >1 yr recommended if patient has history of stent thrombosis or stents in left main artery, multiple vessels, or only remaining patent coronary artery or conduit; continue aspirin perioperatively if clopidogrel discontinued; no role for bridging with glycoprotein IIb/IIIa inhibitors (but small observational pilot study associates inhibitor use with no deaths, myocardial infarction, or need for ­re-exploration, and only 2 bleeding episodes; supports use as bridging therapy)

Strategy for patients with history of recent PTCA: delay elective surgery for 2 wk; continue aspirin perioperatively and discontinue clopidogrel for 2 wk (­6-8 wk if patient has ­bare-metal stent)

Patients with DES: emergency surgery — proceed; ­semi-urgent surgery — if risk for surgical bleeding low, continue DAPT and proceed; if risk for bleeding intermediate and duration of DAPT <1 yr, continue DAPT, proceed with surgery, and manage bleeding episodes that arise; if duration of DAPT >1 yr, discontinue clopidogrel and continue aspirin; continue with aspirin monotherapy if risk for stent thrombosis low; consider bridging therapy or ticagrelor if risk for thrombosis high; if risk for bleeding high, discontinue DAPT and proceed with surgery if risk for thrombosis low; consider bridging therapy or ticagrelor if thrombosis risk high and patient off DAPT; elective surgery — postpone until stent in place >1 yr; address issues described for more urgent procedures

Intraoperative management: control heart rate and blood pressure (b-blockers decrease sympathetic tone, which lowers platelet hyperreactivity); use regional anesthesia with caution (avoid catheters; if patient off DAPT, has DES, and needs postsurgical analgesia, choose ­single-shot spinal or narcotic, or epidural); consider transfusion of platelets or factor VII for patient still on DAPT who experiences significant bleeding episode

Postoperative management: ambulatory surgery not recommended for patients with DES; maintain high index of suspicion for stent thrombosis (ST segment changes, refractory hypotension, new atrioventricular block, and ventricular arrhythmias signal ischemia; immediate thrombectomy indicated)

Readings

Cannesson M et al: Anesthesia for noncardiac surgery in adults with congenital heart disease. Anesthesiology 2009 Aug;111(2):­432-40; Cannesson M et al: Anesthesia in adult patients with congenital heart disease. Curr Opin Anaesthesiol 2009 Feb;22(1):­88-94; Christensen RE et al: Anaesthetic management and outcomes in patients with surgicall corrected ­D-transposition of the great arteries undergoing ­non-cardiac surgery. Br J Anaesth 2010 Jan;104(1):­12-5; Gatzoulis MA et al: Risk factors for arrhythmia and sudden cardiac death late after repair of tetralogy of Fallot: a multicentre study. Lancet 2000 Sep 16;356(9234):­975-81; Held C et al: Ticagrelor versus clopidogrel in patients with acute coronary syndromes undergoing coronary artery bypass surgery: results from the PLATO (Platelet Inhibition and Patient Outcomes) trial. J Am Coll Cardiol 2011 Feb 8;57(6):­672-84; Iakovou I et al: Incidence, predictors, and outcome of thrombosis after successful implantation of ­drug-eluting stents. JAMA 2005 May 4;293(17):­2126-30; Naguib MA et al: A functional understanding of moderate to complex congenital heart disease and the impact of pregnancy. Part II: tetralogy of Fallot, Eisenmenger’s syndrome and the Fontan operation. Int J Obstet Anesth 2010 Jul;19(3):­306-12; Odegard KC et al: Procoagulant and anticoagulant factor abnormalities following the Fontan procedure: increased factor VIII may predispose to thrombosis. J Thorac Cardiovasc Surg 2001 Jun;125(6):­1260-7; Savonitto S et al: Urgent surgery in patients with a recently implanted coronary ­drug-eluting stent: a phase II study of “bridging” antiplatelet therapy with tirofiban during temporary withdrawal of clopidogrel. Br J Anaesth 2010 Mar;104(3):­285-91; Seal R: Adult congenital heart disease. Paediatr Anaesth 2011 May;21(5):­615-22; van Werkum JW et al: ­Long-term clinical outcome after a first angiographically confirmed coronary stent thrombosis: an analysis of 431 cases. Circulation 2009 Feb 17;119(6):­828-34; Wiviott SD et al: Prasugrel versus clopidogrel in patients with acute coronary syndromes. N Engl J Med 2007 Nov 15;357(20):­2001- 1. 5.

Disclosures

In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the planning committee to disclose relevant financial relationships within the past 12 months that might create any personal conflicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, the faculty and planning committee reported nothing to disclose.

Acknowledgements

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CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0 CE contact hours.

Lecture ID:

AN540502

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.

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