An electrocardiogram (ECG), also known as an EKG, is a simple, non-invasive test that measures the heart’s electrical activity. Before surgery, the ECG screens for pre-existing or silent cardiac conditions that could lead to serious complications. The stress of anesthesia and surgery places a significant burden on the heart, potentially exposing underlying issues like unmanaged arrhythmias or unrecognized coronary artery disease. The decision to order a pre-operative ECG is based on an individualized assessment of the patient’s health status and the anticipated cardiac strain of the planned surgery.
Patient Risk Factors Requiring Evaluation
A patient’s medical history contains several conditions that significantly raise the likelihood of needing a pre-operative ECG, even for moderate procedures. A history of ischemic heart disease, which includes previous heart attacks or current angina, is a major predictor of perioperative complications. Similarly, a history of heart failure or a prior stroke indicates a compromised cardiovascular system that may not tolerate the stress of surgery.
Uncontrolled systemic conditions also increase cardiac risk and necessitate closer scrutiny before an operation. Patients with insulin-dependent diabetes mellitus often have silent coronary artery disease, meaning they may not experience typical chest pain symptoms due to nerve damage. Renal insufficiency (serum creatinine level of 2.0 mg/dL or higher) is another strong risk factor because it affects fluid balance and is often linked to underlying cardiovascular disease.
Advanced age is an independent factor that increases risk, with guidelines frequently recommending an ECG for patients over 65 years old scheduled for major surgery. The presence of unexplained symptoms, such as new palpitations, shortness of breath, or chest pain, also mandates a pre-operative ECG regardless of the patient’s age. These clinical markers are used to stratify a patient’s intrinsic vulnerability to a major adverse cardiac event.
Cardiac Stress Level of the Procedure
The type of surgery is a critical variable in the risk assessment. Procedures are broadly categorized into three groups based on the estimated risk of cardiac death or nonfatal heart attack within 30 days of the operation. High-risk surgeries carry a complication rate exceeding five percent and include major vascular operations (e.g., aortic repair) and emergent large-volume surgeries associated with significant blood loss and fluid shifts.
Intermediate-risk surgeries have an estimated cardiac event rate between one and five percent. This category includes intraperitoneal or intrathoracic surgeries, carotid endarterectomy, most orthopedic hip replacement surgeries, and major head and neck operations. Low-risk surgeries, with an event rate of less than one percent, involve superficial procedures, endoscopic treatments, breast surgery, and cataract removal.
The classification of the surgery is the first step in deciding whether an ECG is necessary. High-risk surgery requires an ECG to establish a baseline and screen for occult disease. For intermediate-risk procedures, the need for an ECG depends heavily on the patient’s individual health factors.
The Pre-Operative Risk Assessment Algorithm
Clinicians use a structured, stepwise process to combine patient and surgical risk and make the final decision regarding an ECG. The pathway begins with the surgical risk level. If the procedure is classified as high-risk, a pre-operative ECG is generally indicated. If the surgery is low-risk, further cardiac testing is typically unnecessary, regardless of minor patient risk factors.
The intermediate-risk surgical category is where the patient’s intrinsic risk factors become the deciding component. For patients undergoing intermediate-risk surgery, the presence of one or more clinical risk factors (e.g., history of heart disease, diabetes, or renal disease) will usually prompt an ECG. The patient’s functional capacity, their ability to perform daily activities, is also integrated into this decision-making process.
An inability to achieve four metabolic equivalents (METs)—the equivalent of climbing two flights of stairs or walking briskly—indicates poor functional capacity. This poor capacity may necessitate an ECG even for intermediate-risk surgery. Testing is performed only when the results could potentially change the patient’s perioperative management, such as by initiating medication or delaying the procedure for cardiac optimization.
Situations Where an ECG is Generally Skipped
An ECG is not a mandatory routine test for every person undergoing an operation. It should not be routinely performed in asymptomatic individuals who are scheduled for low-risk, non-cardiac elective surgery. This includes healthy, younger patients (typically under age 50 or 60) who have no personal or family history of heart disease, diabetes, or kidney issues.
For these low-risk individuals, the addition of a pre-operative ECG rarely yields information that affects the surgical outcome or changes the anesthetic plan. Procedures such as minor dermatological excisions or common endoscopic screenings fall into this category. Obtaining an ECG in this population is often seen as a source of unnecessary cost and potential delays.