In patients undergoing noncardiac surgery, preoperative intervention for a cardiac condition is rarely needed simply to reduce the risk of the surgery unless such intervention is indicated separate from the preoperative context.
This is the overriding message of the 2007 guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery issued by the American College of Cardiology (ACC) and American Heart Association (AHA), 1 for which I was privileged to chair the writing committee. This article outlines current best practices in cardiac risk stratification for noncardiac surgery, highlighting key recommendations from the ACC/AHA 2007 perioperative guidelines.
PURPOSE OF THE PREOPERATIVE CARDIAC EVALUATION
Provide clinical judgment, not clearance for surgery
A proper cardiac evaluation prior to noncardiac surgery involves a comprehensive patient assessment that draws on clinical findings, the clinical experience of the consulting physician (typically a cardiologist or internist), and an assessment of the literature. The purpose is not to give medical clearance for surgery but rather to provide informed clinical judgment to the anesthesiologist and the surgical team in terms of the following 1:
- The patient’s current medical status
- Recommendations regarding the management and risk of cardiac problems during the perioperative period
- The patient’s clinical risk profile, to assist with treatment decisions that may affect short- or long-term cardiac outcomes.
Order tests only when results may change management
The consulting physician’s clinical judgment is critical in determining the need to order any specific tests. In general, a test to further define cardiac risk is valid only when its results could change the planned management and lead to a specific intervention. Potential interventions that may result from knowledge gained through testing include:
- Delaying the operation because of unstable symptoms
- Coronary revascularization
- Attempting medical optimization before surgery
- Involving additional specialists or providers in the patient’s perioperative care
- Modification of intraoperative monitoring
- Modification of postoperative monitoring
- Modification of the surgical location, particularly when the procedure is scheduled for an ambulatory surgical center.
The cardiac evaluation should result in an estimation of cardiac risk. If the consulting physician’s estimation of risk is not clearly above or below the threshold for a potential intervention, then further testing may be indicated to further define the need for interventions (ie, reaching the threshold for action).
WHAT TO WORRY ABOUT FIRST: HIGH-RISK CONDITIONS THAT REQUIRE EVALUATION AND TREATMENT
In a recommendation categorized as a Class I, Level B endorsement, * the ACC/AHA 2007 perioperative guidelines specify four active cardiac conditions for which an evaluation and treatment are required before noncardiac surgery 1:
- Unstable coronary syndromes , including unstable or severe angina or recent myocardial infarction (MI). These syndromes should be the first and most important consideration. Unstable angina is a hypercoagulable state, as is recent MI. The hypercoagulability of these conditions is compounded by the hypercoagulability induced by the perioperative setting itself. As a result, the rate of perioperative MI or death in the setting of unstable angina is as high as 28%. 2 In the case of unstable coronary syndromes, delaying surgery is appropriate if the risks of the surgery are deemed greater than its potential benefits.
- Decompensated heart failure , defined as New York Heart Association functional class IV disease or worsening or new-onset heart failure.
- Significant arrhythmias , defined as high-grade or Mobitz II atrioventricular block, third-degree atrioventricular heart block, symptomatic ventricular arrhythmias, supraventricular arrhythmias with uncontrolled ventricular rate, symptomatic bradycardia, and newly recognized ventricular tachycardia.
- Severe valvular disease , defined as severe aortic stenosis and symptomatic mitral stenosis.