Assessment of cardiac risk is an essential component of presurgical work-up of both inpatients and outpatients. Beyond allowing a physician to calculate the risk of experiencing cardiac events (ie, myocardial infarction or sudden cardiac death) in the future, preoperative assessment might provide a clinical risk stratification profile that the patient, primary physician, anesthesiologist, surgeon, and nonphysician caregivers can use in making treatment decisions that could influence short- and long-term cardiac outcomes.1
In this article, we will focus on preoperative cardiac assessment in patients undergoing noncardiac surgery, including aortic and other major vascular surgery, head and neck surgery, orthopedic surgery, and even transplantation. As a hospitalist, you might be involved in the care of patients before and after surgery, and assessment of cardiac function is crucial to a successful surgery, as well as a successful outcome for these patients. It is important that you are aware of cardiac risk associated with noncardiac surgery, the cardiac testing methods available to assess risk, and which types of cardiac imaging are appropriate and safe for each patient.
The risk of perioperative cardiac complications depends on the condition of the patient prior to surgery, the prevalence of comorbidities, and the type of surgical procedure. Preoperative assessment begins with an evaluation of the patient’s clinical risk factors using one of the scoring conventions established first by Goldman in 1977 and updated throughout the past decades by further research.2 The Revised Cardiac Risk Index (RCRI), developed in 1999 by Lee et al,3 is currently the most widely used tool for assessing cardiac risk in noncardiac surgery. This index identifies six predictors of major cardiac complications4:
- High-risk surgical procedure, defined as:
- Thoracic, abdominal, or pelvic vascular (eg, aorta, renal, mesenteric) surgery
- Ischemic heart disease, defined as:
- History of myocardial infarction
- History of or current angina
- Use of sublingual nitroglycerin
- Positive exercise test
- Q waves on electrocardiogram (ECG)
- Patients who have undergone PTCA or CABG and who have chest pain presumed to be of ischemic origin
- Heart failure, defined as*
- Left ventricular failure by physical examination (ie, pulmonary congestion)
- History of paroxysmal nocturnal dyspnea
- History of pulmonary edema
- S3 or bilateral rales on physical examination
- Pulmonary edema on chest X-ray
- Cerebrovascular disease, defined as:
- History of transient ischemic attack
- History of cerebrovascular accident
- Insulin-dependent diabetes mellitus; and
- Chronic renal insufficiency, defined as baseline creatinine >2.0 mg/dL
*Use of β-blockers must be individualized and used with caution in patients with heart failure.
This scoring system allows you to classify your patients as having low (no RCRI criteria), intermediate (one or two RCRI criteria), or high (three or more RCRI criteria) risk for cardiac complications during surgery.4
Adapted from Fleisher, et al. Circulation. 2009;120:e169-276.
Noninvasive Diagnostic Testing
Preoperative testing can be used to answer questions brought up by a patient’s medical history and physical examination. However, no cardiovascular test should be performed if the results will not change perioperative management. The impact of preoperative cardiac testing may differ according to the situation: medical treatment may be optimized, the surgical procedure may be modified, anaesthetic management may be adjusted, the risk/benefit ratio of a surgical procedure may be re-evaluated, or revascularization may occur.5
Traditionally, exercise ECG has been useful for evaluating individuals for the presence of coronary artery disease (CAD).6 Stress echocardiography (echo) provides similar diagnostic and prognostic accuracy to radionuclide stress perfusion imaging but at a lower cost.7 For patients with limited capacity for exercise stress testing, there are several options for pharmacologic stress imaging, which mimics the coronary vasodilatory effect of exercise stress. Instead of exercise testing, for patients with functional limitations, pharmacologic stress can be used.4
There are several stress nuclear imaging options for high-risk patients and those with important abnormalities on their resting ECG that interfere with diagnosis (eg, left bundle-branch block, LV hypertrophy with “strain” pattern, or digitalis effect).1 Myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT) is a widely used imaging technique for preoperative evaluation.* It involves IV administration of a small quantity of a radiotracer (eg, technetium-99m radiopharmaceutical), followed by imaging at rest and during exercise or pharmacologic stress. Detection of CAD is based on the relative difference in blood flow distribution in the myocardium during rest and stress, revealing areas of insufficient coronary blood flow due to coronary stenosis. A positive test is associated with an increased risk of peri- and postoperative cardiac complications.3 Newer imaging modalities, including cardiac magnetic resonance imaging, cardiac computed tomography, coronary calcium scoring, and positron emission tomography (PET) MPI are also being applied to preoperative assessment of patients undergoing noncardiac surgery.6 An understanding of the available modalities can ensure that patients are being assessed appropriately; we will give an overview of the cardiac imaging modalities in a future newsletter on imaging reports.
Preoperative assessment of cardiac risk in patients prior to noncardiac surgery lies in the hands of all healthcare providers who make clinical decisions for patients. As a leader in the management of patient care, hospitalists have a unique opportunity to ensure that each patient is treated appropriately, based on clinical evidence. Your role in advocating for suitable preoperative assessment might extend beyond individual patients, and into the development and enforcement of hospital protocols, based on current and evolving guidelines.
*To determine whether SPECT MPI is appropriate for your patient, you may refer to the 2009 appropriate use criteria, which are now available in smartphone applications; visit AstellasApps.com for more information.
Matthew Landler, MD, from the Northwestern University Feinberg School of Medicine, is the consultant for The Heart and Hospital Medicine series. Dr. Landler is a consultant for Astellas Pharma US, Inc.