Updated guidelines on cardiovascular evaluation before noncardiac surgery: A view from the trenches

CLINICAL RISK FACTORS

Coronary artery disease

Ischemic symptoms, a history of myocardial infarction, and elevated cardiac biomarkers are individually associated with perioperative risk of morbidity and death. The risk is modified by how long ago the infarction occurred, whether the patient underwent coronary revascularization, and if so, what type (bypass grafting or percutaneous coronary intervention). A patient with acute coronary syndrome (currently or in the recent past) is at higher risk, and should have elective surgery delayed and be referred for cardiac evaluation and management according to guidelines.

Heart failure

In terms of posing a risk for major adverse cardiac events, heart failure is at least equal to coronary artery disease, and is possibly worse. Its impact depends on its stability, its symptoms, and the patient’s left ventricular function. Symptomatic decompensated heart failure and depressed left ventricular function (ejection fraction < 30% or 40%) confer higher risk than asymptomatic heart failure and preserved left ventricular function. However, evidence is limited with respect to asymptomatic left ventricular dysfunction and diastolic dysfunction. Patients with stable heart failure treated according to guidelines may have better perioperative outcomes.

Valvular heart disease

Significant valvular heart disease is associated with increased risk of postoperative cardiac complications. This risk depends on the type and severity of the valvular lesion and type of noncardiac surgery, but can be minimized by clinical and echocardiographic assessment, choosing appropriate anesthesia, and closer perioperative monitoring. Aortic and mitral stenosis are associated with greater risk of perioperative adverse cardiac events than regurgitant valvular disease.

Echocardiography is recommended in patients suspected of having moderate to severe stenotic or regurgitant lesions if it has not been done within the past year or if the patient’s clinical condition has worsened.

The purpose is not to 'get clearance' but to evaluate the patient's medical status and risk of complications

If indicated, valvular intervention can reduce perioperative risk in these patients. Even if the planned noncardiac surgery is high-risk, it may be reasonable to proceed with it (using appropriate perioperative hemodynamic monitoring, which is not specified but typically would be with an arterial line, central line, and possibly a pulmonary arterial catheter) in patients who have asymptomatic severe aortic or mitral regurgitation or aortic stenosis. Surgery may also be reasonable in patients with asymptomatic severe mitral stenosis who are not candidates for repair.

Arrhythmias

Cardiac arrhythmias and conduction defects are often seen in the perioperative period, but there is only limited evidence as to how they affect surgical risk. In addition to their hemodynamic effects, certain arrhythmias (atrial fibrillation, ventricular tachycardia) often indicate underlying structural heart disease, which requires further evaluation before surgery.

The new guidelines refer the reader to previously published clinical practice guidelines for atrial fibrillation,¹¹ supraventricular arrhythmias,¹² and device-based therapy.¹³

ALGORITHM FOR PREOPERATIVE CARDIAC ASSESSMENT

The new algorithm for evaluating a patient who is known to have coronary artery disease or risk factors for it has seven steps (Figure 1).^{1,11,12,14–17} It differs from the previous algorithm in several details:

• Instead of listing the four active cardiac conditions for which elective surgery should be delayed while the patient is being evaluated and treated (unstable coronary syndrome, decompensated heart failure, significant arrhythmias, severe valvular heart disease), the new version specifically asks about acute coronary syndrome and recommends cardiac evaluation and treatment according to guidelines. A footnote directs readers to other clinical practice guidelines for symptomatic heart failure,¹⁴ valvular heart disease,¹⁵ and arrhythmias.^11,12
• Instead of asking if the procedure is low-risk, the guidelines recommend estimating risk of major adverse cardiac events on the basis of combined clinical and surgical risk and define only two categories: low or elevated. Patients at low risk proceed to surgery with no further testing, as in the earlier algorithm.
• "Excellent" exercise capacity (> 10 metabolic equivalents of task [METs]) is separated from "moderate/good" (4–10 METs), presumably to indicate a stronger recommendation, but patients in both categories proceed to surgery as before.
• If the patient cannot exercise to at least 4 METs, the new algorithm asks whether further testing will affect decision-making or perioperative care (an addition to the previous algorithm). This entails discussing with the patient and perioperative team whether the original surgery will be performed and whether the patient is willing to undergo revascularization if indicated. If so, pharmacologic stress testing is recommended. Previously, this decision also included the number of RCRI factors as well as the type of surgery (vascular or nonvascular).
• If testing will not affect the decision or if the stress test is normal, in addition to recommending proceeding to surgery according to guidelines the new algorithm also lists an option for alternative strategies, including palliation.
• If the stress test is abnormal, especially with left main disease, it recommends coronary revascularization according to the 2011 clinical practice guidelines.^18,19