orbidity and mortality from cardiac complications are the most common significant adverse events in the perioperative period. Up to 1 percent of the 100 million adults having noncardiac surgery each year will be affected, and one in four will die. The goal is to lower the risk in the preoperative period by identifying patients with modifiable conditions or with a high risk for perioperative cardiac events. Yet questions and controversies surround the various diagnostic and therapeutic methods.

First published in 1996, the guidelines for cardiac evaluation before noncardiac surgery by the American College of Cardiology/American Heart Association (ACC/AHA) have become the national standard of care. The revision in 2007 reduced recommendations for preoperative noninvasive stress testing and revascularization.¹ This altered approach was driven by the recognition that frequently unpredictable coronary plaque rupture of minor lesions and thrombus are the culprits in 50 percent of fatal myocardial infarctions (MI) perioperatively. Revascularization alone, not recommended for less critical stenoses, does not prevent plaque rupture.

The ACC/AHA guidelines are organized in a stepwise approach. Management is determined by the first recommendation that applies to a particular patient, and there is no need to progress through the entire algorithm.

Step 1 considers the urgency of the surgery. If emergency surgery precludes further assessment, the focus is on perioperative surveillance (e.g., serial ECGs, enzymes, monitoring) and risk reduction (e.g., beta-blockers with strict control of heart rate, statins, pain management). Clinical predictors, exercise capacity and level of surgical risk guide further diagnostic and therapeutic interventions.

Step 2 considers an active cardiac condition such as an acute MI, unstable or severe angina, decompensated heart failure, severe valvular disease (e.g., severe aortic stenosis) or significant arrhythmias (e.g., ventricular tachycardia or atrial fibrillation with a rapid rate). These conditions warrant postponement for all except life-saving emergencies. Traditionally, surgery was delayed for patients with an MI within the previous three to six months. More recent evidence suggests that an acute MI, occurring within the past seven days, warrants postponing elective surgeries. A recent MI, within the past eight to 30 days with evidence of myocardium at risk (because of persistent symptoms or the results of stress testing) is a high-risk condition. If the recent MI is without evidence of myocardium at risk, the risk is simply equivalent to that of coronary artery disease (CAD).

Step 3 considers the surgical severity. Patients without active cardiac conditions who need low-risk surgery, such as endoscopic or superficial procedures, or ambulatory surgeries (cardiac risk generally < 1 percent) do not need cardiac testing before surgery.

Step 4 assesses the patient’s functional capacity. Asymptomatic patients with an average exercise capacity (can walk up two flights of stairs or four blocks) can proceed to surgery.

Step 5, the last and most complicated, considers patients with poor or indeterminate functional capacity scheduled for vascular, intermediate or high-risk procedures. The number of clinical predictors alters the recommendations for, and likely benefit of, cardiac testing. The clinical predictors were derived from the revised cardiac risk index (RCRI), which identified ischemic heart disease, heart failure, cerebrovascular disease, diabetes and renal insufficiency as important co-morbidities. A cohort study showed an incidence of major cardiac events of 0.4 percent, 0.9 percent, 7 percent or 11 percent in patients with 0, 1, 2 or 3 risk predictors, respectively.² Patients with none of the clinical predictors proceed to surgery. Patients with three or more clinical risk factors who need vascular surgery are most likely to benefit from further testing. The guidelines recommend further testing only “if it will change management.” Patients with one to two clinical predictor(s) who need intermediate-risk surgery (1 percent to 5 percent risk of cardiac complications; orthopedic, intra-abdominal and intrathoracic procedures) or vascular surgery can proceed to surgery with heart rate control or undergo noninvasive testing if it will change management. The guidelines specifically state, “there are insufficient data to determine the best strategy.” Factors to consider are the urgency of the noncardiac surgery (e.g., patients with cancer), the life-expectancy of the individual and the potential long-term benefits of medical management versus revascularization.

Risk factors for CAD (e.g., smoking, family history, hypercholesterolemia, age and hypertension) have not been shown to predict perioperative cardiac morbidity.

Noninvasive stress testing and coronary revascularization before noncardiac surgery lack definitive benefits for risk reduction. The only randomized prospective study of revascularization (coronary artery bypass grafting [CABG] or percutaneous coronary intervention [PCI]) versus medical management failed to show a difference in outcome.³ The study considered intermediate- to high-risk patients with known CAD who needed major vascular surgery. Other retrospective and observational studies have also failed to show a benefit of coronary revascularization before noncardiac surgery. Additionally, optimal medical management in stable, multivessel disease has been shown to be superior to revascularization in nonoperative studies.^4,5

Noncardiac surgery soon after revascularization (CABG or PCI with or without stents) is associated with high rates of perioperative morbidity and mortality.^6,7 Patients who need noncardiac surgery within a year of revascularization are not good candidates for implantation of drug-eluting stents (DES). If revascularization is necessary, CABG or PCI without stenting or with a bare metal stent (BMS) should be considered.⁸

DES substantially impair arterial healing compared to BMS.⁹ Long-term, this decreases the incidence of in-stent stenosis. However, delay in endothelialization may increase the risk of thrombosis if antiplatelet agents are not used due to a persistent thrombogenic surface. Thrombotic events are a major cause of death after PCI. What causes thrombosis with DES, how often or under what circumstances it occurs, or the risk of occurrence in a given patient is unclear.

A joint science advisory has been published with the following selected recommendations:⁸

• In patients who need PCI and are likely to require invasive procedures within the next 12 months, consideration should be given to implantation of a BMS or balloon angioplasty alone instead of a DES.

• There are potentially catastrophic risks of premature discontinuation of thienopyridine (e.g., clopidogrel or ticlopidine) therapy. The patient’s cardiologist should be contacted to discuss optimal strategies of antiplatelet therapy.

• Elective procedures involving risk of bleeding should be deferred until an appropriate course of thienopyridine therapy has been completed (12 months after DES and one month after BMS).

• Patients with a DES who need a procedure that mandates discontinuation of thienopyridine therapy should continue aspirin and restart the thienopyridine as soon as possible.

Neuraxial techniques (spinal and epidural) are not contraindicated in patients taking aspirin, but performing these techniques is a concern in patients taking thienopyridine therapy. The risk of spinal hematoma with ticlopidine, clopidogrel and glycoprotein IIb/IIIa antagonists is unknown. Based on labeling and the guidelines of the American Society of Regional Anesthesia and Pain Medicine (ASRA), clopidogrel therapy should be discontinued seven days before neuraxial blockade.¹⁰

A preoperative evaluation may be the first time a patient has been assessed for cardiovascular disease and long-term risk modification. Decisions to revascularize patients before noncardiac surgery should be made only after evaluating the risk of perioperative adverse events, the risks and benefits of risk reduction (medications, CABG, PCI, stents), the benefits of the noncardiac surgery, the risks associated with delaying surgery, and patient preferences. The ACC/AHA guidelines state: “The overriding theme of this document is that intervention is rarely necessary to simply lower the risk of surgery unless such intervention is indicated irrespective of the preoperative context.”¹ Ideally, a dialogue between patient, surgeon, cardiologist and anesthesiologist may assist decision-making.

The ACC/AHA guidelines also discuss perioperative implications of hypertension, heart failure, valvular disease, cardiomyopathies, arrhythmias, conduction abnormalities, pacemakers and implantable cardioverter-defibrillators (ICDs). ASA has a practice advisory on the perioperative management of pacemakers and ICDs.¹¹

Patients with ICDs are at risk for adverse events from electrical/magnetic interference (e.g., electrocautery). Unexpected cardioversion with patient movement during intracranial, spinal or ocular procedures can have catastrophic results. Central line placement can trigger cardioversion. Consultation with the device manufacturer, cardiologist or the electrophysiology service may be needed. Ideally, ICDs should be interrogated preoperatively. Anti-tachyarrhythmia functions are disabled before surgical procedures if interference or unexpected patient movement is undesirable.¹¹ ECG monitoring and external cardioversion or defibrillation capabilities must be available. It may not be appropriate to care for patients with ICDs in some facilities. Patients usually have a wallet card with important designations and phone numbers.

Newer-generation devices are complex, and reliance on a magnet to disable them, except in emergencies, is not recommended. Some devices are programmed to ignore magnet placement, or magnets permanently disable anti-tachyarrhythmic therapy. Also, a magnet may simply suspend anti-shock therapies in some ICDs while the magnet is in place. Unlike with conventional pacemakers, magnets do not change pacing function of an ICD. Magnets affect only the anti-tachycardia function of an ICD. If the ICD was reprogrammed preoperatively or a magnet was used at any time, the device should be re-interrogated and re-enabled before the patient leaves a monitored setting.

Equally important as device programming is evaluation of coexisting cardiac diseases. Patients with ICDs invariably have heart failure, ischemic or valvular disease, cardiomyopathies or potentially lethal arrhythmias. These patients must be identified and managed in collaboration with a cardiologist.

Because cardiac complications are the leading cause of perioperative morbidity and mortality, anesthesiologists must be up to date on the latest evidence-based recommendations and active in decision-making and management of at-risk patients.

References:
1. Fleisher LA, Beckman JA, Brown KA, et al. ACC/AHA 2007 Guidelines on Perioperative Cardiovascular Evaluation and Care for Noncardiac Surgery. J Am Coll Cardiol. 2007; 50;e159-241. http://www.acc.org/qualityandscience/clinical/guidelines/Periop_Fulltext_2007.pdf. Accessed on February 20, 2008.
2. Lee TH, Marcantonio ER, Mangione CM, et al. Derivation and prospective validation of a simple index for prediction of cardiac risk of major noncardiac surgery. Circulation. 1999; 100:1043-1049.
3. McFalls EO, Ward HB, Mortiz TE, et al. Coronary-artery revascularization before elective major vascular surgery. N Engl J Med. 2004; 351:2795-2804.
4. Hueb W, Lopes NH, Gersh Bj, et al. Five-year follow-up of the Medicine, Angioplasty, or Surgery Study (MASS II): A randomized controlled clinical trial of 3 therapeutic strategies for multivesssel coronary artery disease. Circulation. 2007; 115:1082-1089.
5. Boden WE, O’Rourke RA, Teo KK, et al. Optimal medical therapy with or without PCI for stable coronary disease. N Engl J Med. 2007; 456:1503-1516.
6. Breen P, Wee JW, Pomposelli F, Park KW. Timing of high-risk vascular surgery following coronary artery bypass surgery: A 10-year experience from an academic medical centre. Anaesthesia. 2004; 59:422-227.
7. Shouten O, van Domburg RT, Bax JJ, et al. Noncardiac surgery after coronary stenting: Early surgery and interruption of antiplatelet therapy are associated with an increase in major adverse cardiac events. J Am Coll Cardiol. 2007; 49:122-124.
8. Grines CL, Bonow RO, Casey DE, 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. J Am Coll Cardiol. 2007; 49:734-739.
9. Joner M, Finn AV, Farb A, et al. Pathology of drug-eluting stents in humans: Delayed healing and late thrombotic risk. J Am Coll Cardiol. 2006; 48:193-202.
10. Horlocker TT, Wedel DJ, Benzon H, et al. Regional anesthesia in the anticoagulated patient: Defining the risks (the second ASRA Consensus Conference on Neuraxial Anesthesia and Anticoagulation). Reg Anesth Pain Med. 2003; 28:172-197.
11. American Society of Anesthesiologists Task Force on Perioperative Management of Patients with Cardiac Rhythm Management Devices. Practice advisory for the perioperative management of patients with cardiac rhythm management devices: Pacemakers and implantable cardioverter-defibrillators. American Society of Anesthesiologists. Anesthesiology. 2005; 103:186-198.

Bobbie Jean Sweitzer, M.D., is Associate Professor, Department of Anesthesia and Critical Care, and Director, Anesthesia Perioperative Medicine Clinic, University of Chicago.