Should all patients have a resting 12-lead ECG before elective noncardiac surgery?
What an ECG can tell us
Abnormalities such as left ventricular hypertrophy, ST-segment depression, and pathologic Q waves on a preoperative ECG in a patient undergoing an elevated-risk surgical procedure may predict adverse perioperative cardiac events.3,6
In a retrospective study of 23,036 patients, Noordzij et al7 found that in patients undergoing elevated-risk surgery, those with an abnormal preoperative ECG had a higher incidence of cardiovascular death than those with a normal ECG. However, a preoperative ECG was obtained only in patients with established coronary artery disease or risk factors for cardiovascular disease. Hence, although an abnormal ECG in such patients undergoing elevated-risk surgery was predictive of adverse postoperative cardiac outcomes, we cannot say that the same would apply to patients without these characteristics undergoing elevated-risk surgery.
In a prospective observational study of patients with known coronary artery disease undergoing major noncardiac surgery, a preoperative ECG was found to contain prognostic information and was predictive of long-term outcome independent of clinical findings and perioperative ischemia.8
CURRENT GUIDELINES AND RECOMMENDATIONS
Several guidelines address whether to order a preoperative ECG but are mostly based on low-level evidence and expert opinion.1,2,6,9
Current guidelines recommend obtaining a preoperative ECG in patients with known coronary, peripheral arterial, or cerebrovascular disease.1,6,9
Obesity and associated comorbidities such as coronary artery disease, heart failure, systemic hypertension, and sleep apnea can predispose to increased perioperative complications. A preoperative 12-lead ECG is reasonable in morbidly obese patients (body mass index ≥ 40 kg/m2) and in obese patients (body mass index ≥ 30 kg/m2) with at least one risk factor for coronary artery disease or poor exercise tolerance, or both.10
Liu et al11 looked at the predictive value of a preoperative 12-lead ECG in 513 elderly patients (age ≥ 70) undergoing noncardiac surgery and found that electrocardiographic abnormalities were not predictive of adverse cardiac outcomes. In this study, although electrocardiographic abnormalities were common (noted in 75% of the patients), they were nonspecific and less useful in predicting postoperative cardiac complications than was the presence of comorbidities.11 Age alone as a cutoff for obtaining a preoperative ECG is not predictive of postoperative outcomes and a preoperative ECG is not warranted in all elderly patients. This is also reflected in current ACC/AHA guidelines on perioperative cardiovascular evaluation1 and is a change from prior ACC/AHA guidelines when age was used as a criterion for preoperative ECGs.12
Current guidelines do not recommend getting a preoperative ECG in asymptomatic patients undergoing low-cardiac-risk surgery.1,4,9
Although the ideal time for ordering an ECG before a planned surgery is unknown, obtaining one within 90 days before the surgery is considered adequate in stable patients in whom an ECG is indicated.1
BACK TO OUR PATIENT
On the basis of current evidence, our patient does not need a preoperative ECG, as it is unlikely to alter his perioperative management and instead may delay his surgery unnecessarily if any nonspecific changes prompt further cardiac workup.
CLINICAL BOTTOM LINE
Although frequently ordered in clinical practice, preoperative electrocardiography has a limited role in predicting postoperative outcome and should be ordered only in the appropriate clinical setting.1 Moreover, there is little evidence that outcomes are better if we obtain an ECG before surgery. The clinician should consider patient factors and the type of surgery before ordering diagnostic tests, including electrocardiography.
In asymptomatic patients undergoing nonemergent surgery:
- It is reasonable to obtain a preoperative ECG in patients with known coronary artery disease, significant arrhythmia, peripheral arterial disease, cerebrovascular disease, chronic heart failure, or other significant structural heart disease undergoing elevated-cardiac-risk surgery.
- Do not order a preoperative ECG in asymptomatic patients undergoing low-risk surgery.
- Obtaining a preoperative ECG is reasonable in morbidly obese patients and in obese patients with one or more risk factors for coronary artery disease, or poor exercise tolerance, undergoing high-risk surgery.
