Lee A. Fleisher, MD, FACC, FAHA

1. What is the natural history of perioperative cardiac morbidity?

    Perioperative cardiac morbidity occurs most commonly during the first 3 postoperative days and includes perioperative myocardial infarction (MI), unstable angina, cardiac death, and nonfatal cardiac arrests. Previously, the peak incidence of perioperative MI was thought to occur during postoperative day 3, although recent studies have suggested it occurs earlier and may arise most commonly in the first 48 hours. Additionally, the mortality from a perioperative cardiac MI has decreased from previous rates of 30% to 50% to approximately 12%. A large number of patients also demonstrate isolated biomarker elevations, which are predictive of worse long-term, but not short-term, survival.

2. What is the cause of perioperative cardiac morbidity?

    The cause of perioperative MI is multifactorial. The postoperative period is associated with a stress response, which includes the release of catecholamines and cortisol, resulting in tachycardia and hypertension. The tachycardia can lead to supply/demand mismatches distal to a critical coronary stenosis, causing myocardial ischemia, and, if prolonged, can lead to perioperative MI. Tissue injury, tachycardia, and the hypercoagulable state also leads to plaque rupture and acute thrombosis, potentially resulting in a perioperative MI. Therefore, many perioperative events will not be predicted by identifying critical stenoses or by preoperative imaging. Additionally, perioperative strategies to reduce cardiac morbidity require a multimodal approach of both reducing supply/demand mismatches and reducing the risk of acute thrombosis.

3. What are the strongest predictors of perioperative cardiac events?

    For some specific patients, surgery represents a very high risk of cardiac complications and either therapy should be initiated preoperatively or the benefits of surgery must significantly outweigh the risks if the decision is to proceed to surgery. According to the 2009 American College of Cardiology Foundation/American Heart Association (ACCF/AHA) Guidelines on Perioperative Cardiovascular Evaluation, active cardiac conditions for which the patient should undergo evaluation and treatment before noncardiac surgery include unstable coronary syndromes, active heart failure, severe valvular disease, and severe arrhythmias. Specific conditions within these general categories are shown in Table 56-1. Analysis of administrative data suggests that the elevated risk of a recent MI continues for at least the first 60 days.

4. What is the revised cardiac risk index (RCRI) and how is it used clinically?

    Cardiac risk indices for perioperative risk stratification have been used in clinical practice for more than 30 years. These indices do not inform clinicians on how to modify perioperative care specifically, but they do provide a baseline assessment of risk and the value of different intervention strategies. Calculation of an index is not a substitute for providing detailed information of the underlying heart disease, its stability, and ventricular function. The RCRI was developed by studying more than 5000 patients and identifying six risk factors, including the following:

In determining the need and value of preoperative testing and interventions, the ACCF/AHA guidelines incorporate the number of risk factors from the RCRI, other than high-risk surgery, which is incorporated elsewhere. Importantly, diabetes (without regard to type of treatment) is considered one of the risk factors, as opposed to insulin treatment.

5. What is the importance of exercise capacity?

    Numerous studies have demonstrated the importance of exercise capacity on overall perioperative morbidity and mortality. Based on several of these studies, patients can be dichotomized into poor functional capacity (less than 4 metabolic equivalents [METS]) versus moderate or excellent exercise capacity. Patients with moderate to excellent exercise capacity rarely need further testing before noncardiac surgery.

6. What is the influence of the surgical procedure on the decision to perform further diagnostic testing?

    In all patients, regardless of the type of surgery, determination of the presence of active cardiac conditions is first and foremost, because proceeding to surgery should only be done after assessing and potentially treating these conditions. Low-risk surgeries (those associated with a perioperative cardiac morbidity and mortality less than 1%) rarely, if ever, require a change in management based on the results of a diagnostic test. The most common such procedures are those performed on an outpatient basis. Multiple studies have focused on patients undergoing vascular surgery, particularly open aortic and lower extremity revascularization. Therefore, these patients are treated uniquely in the assessment of the need to perform diagnostic testing, based on the extensive evidence and the high perioperative cardiac morbidity and mortality, often in the range of 5% or greater. In the intermediate group of procedures, a gradation of risk is based on the specific surgical procedures and the institution-specific risk is critical to determine if further diagnostic testing would add value. For example, increased surgical volume is associated with lower perioperative risk, and preoperative testing may not lead to changes in management in such institutions.

7. How do the ACCF/AHA guidelines suggest an approach to preoperative evaluation?

    The algorithm from the 2009 guidelines can be found in Figure 56-1. Importantly, any decision to perform diagnostic testing based on the algorithm must incorporate the value of the information to change perioperative management. Changes in management can include the decision to undergo coronary revascularization, but may also include decisions by the patient to forego surgery and decisions by the surgeon to change the type of procedure. The algorithm incorporates the urgency of surgery, clinical risk factors, and functional status. For patients with risk factors, who are undergoing vascular surgery, the studies demonstrate no difference in outcomes between coronary revascularization before noncardiac surgery and proceeding directly to the noncardiac surgery, incorporating heart rate control perioperatively. The class of recommendation and strength of evidence, based on the ACCF/AHA criteria, is shown on the algorithm.

8. What is the value of coronary revascularization before noncardiac surgery?

    Previously it was thought that patients who had undergone prior coronary artery bypass grafting (CABG) had a lower rate of perioperative cardiac morbidity compared with patients with a similar extent of coronary disease who had not undergone revascularization. However, several randomized trials have questioned the value of acute revascularization before noncardiac surgery. In the Coronary Artery Revascularization Prophylaxis (CARP) trial, 500 patients were randomized to coronary revascularization versus medical therapy and followed for up to 6 years. Importantly, patients with left main coronary artery (LMCA) disease, severe triple vessel disease with depressed ejection fraction, and severe comorbidities were excluded. Two-thirds of the patients who underwent coronary revascularization had percutaneous coronary interventions (PCI). There was no difference in either perioperative or long-term morbidity and mortality. In the Dutch Echocardiographic Cardiac Risk Evaluation Applying Stress Echocardiography II (DECREASE-II) trial, patients with one to two clinical risk factors were randomized to preoperative testing and revascularization or proceeded directly to vascular surgery with tight heart rate control; again no difference in outcome was detected. In the DECREASE-V pilot study of 101 patients with extensive coronary artery disease, no difference in perioperative cardiac morbidity and mortality was seen between the revascularization and medical therapy arms of the trial, although the authors were able to demonstrate better short- and long-term outcomes in the subset of patients for whom revascularization was successful. However, the quality of the data from the DECREASE trials has recently been questioned. Similarly, analysis of the nonrandomized patients in the CARP database demonstrated improved perioperative outcomes in the subset of patients with LMCA disease who underwent coronary revascularization. Therefore, current high-quality evidence suggests that coronary revascularization before major noncardiac surgery is of limited or no benefit in stable patients and in those with only 1 or 2 risk factors; however, there may be benefit to coronary artery bypass grafting in patients with LMCA or severe triple vessel disease.

9. What is the concern regarding surgery in patients with a previous PCI?

    Patients who have previously undergone PCI have not been shown to have a significant difference in perioperative outcomes compared with case-matched controls. Importantly, the risk of thrombosis after PCI is high and the hypercoagulable perioperative state increases the probability of this occurring. Multiple cohort studies and case reports have reported the occurrence of acute thrombosis and perioperative MI at the site of coronary stents. In patients with bare metal stents, this most commonly occurs in patients who have undergone noncardiac surgery within 30 days. In patients with drug-eluting stents, the higher rate of acute thrombosis can be seen for at least 1 year, and there are data to suggest it continues after this period. Therefore, the current recommendation is to delay elective surgery for at least 14 days after balloon angioplasty (without stenting), at least 30 days after placement of bare metal stents, and until 1 year after placement of drug-eluting stents.

10. How should antiplatelet agents be managed in the perioperative period?

    The consensus statement from the ACCF/AHA in 2007, as well as the perioperative guidelines, advocate continuing aspirin in all patients who have had a previous PCI. In patients currently taking a P2Y12 inhibitor particularly those within 30 days of placement of a bare metal stent or 1 year for drug-eluting stents, the agent should either be continued, or discontinued for a short period and restarted as quickly as possible in the postoperative period. The critical period may be 5 days for the P2Y12 inhibitor.

11. How should beta-adrenergic blocking agents (β-blockers) be managed in the perioperative period?

    Based on cohort studies and consensus opinion, patients who are receiving chronic β-blocker therapy at the time of surgery should be continued on these agents to avoid the risk of β-blocker withdrawal, which is associated with tachycardia and an increased incidence of perioperative MI. Currently, controversy exists regarding the acute administration of β-blocker therapy for those patients at high risk of perioperative event but not currently taking these agents. The DECREASE trial and subsequent cohort studies from the Erasmus group have demonstrated improved outcome in patients with known coronary heart disease with the administration of bisoprolol at lower doses, started a minimum of 7 days prior to surgery and titrated to a heart rate less than 80 beats/min, although there is currently controversy regarding the quality of the study data published by Poldermans. In the Perioperative Ischemic Evaluation (POISE) study, 8351 patients were randomized to high-dose metoprolol succinate, a long-acting agent, which was compared with placebo. Although nonfatal perioperative MIs were reduced, the incidence of death and stroke was significantly increased, and was associated with higher rates of hypotension. Therefore, initiating high-dose β-blocker therapy in the perioperative period without titration to heart rate and blood pressure could lead to greater harm than benefit and should not be considered. However, heart rate control remains a critical approach to reducing perioperative cardiac morbidity and initial treatment should focus on treating the cause of tachycardia, including pain management, after which, careful titration of β-blockers is appropriate. In patients who should be taking β-blockers (independent of noncardiac surgery) for underlying coronary artery disease, initiation and titration a week or more in advance of surgery has been advocated based on data by some authors, but the safest protocol is controversial. There is also nonrandomized data to suggest that atenolol is associated with improved outcome compared to metoprolol.

12. How should statins be managed in the perioperative period?

    Previously there was concern that continuation of statins in the perioperative period could lead to an increased incidence of rhabdomyolysis, and most clinicians discontinued these agents before surgery. However, evidence has accumulated that statin therapy is protective and that withdrawal is harmful. There is randomized data to suggest that starting statin therapy at least 7 days in advance in high-risk patients is associated with improved outcome. In the 2009 perioperative guidelines, the committee advocated continuing statins in all patients currently taking these agents.

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