When is an electrocardiogram (ECG) recommended?

When to Obtain an Electrocardiogram (ECG)

An ECG should be obtained for all patients with chest pain unless a noncardiac cause is evident, and if an ECG is unavailable in the office setting, the patient should be referred to the emergency department. 1

Primary Indications for ECG

Symptoms Requiring Immediate ECG

• Chest pain or chest pain equivalents (primary indication) 1
• Dizziness or syncope 1
• Palpitations 1
• Shortness of breath (especially in patients ≥50 years) 2
• Unexplained fatigue, weakness, or prostration 1

High-Risk Populations Requiring ECG

• Patients with known cardiovascular disease for baseline evaluation 1
• Patients with suspected acute coronary syndrome (ACS) 1
• Patients ≥50 years with shortness of breath, altered mental status, upper extremity pain, syncope, or generalized weakness 2
• Patients ≥80 years with abdominal pain or nausea/vomiting 2

Specific Clinical Scenarios

Acute Chest Pain Management

• An ECG should be acquired and interpreted within 10 minutes of arrival for patients with acute chest pain 1
• If an initial ECG is nondiagnostic but clinical suspicion for ACS remains high, serial ECGs should be performed, especially when symptoms persist or the clinical condition deteriorates 1
• In patients with intermediate-to-high clinical suspicion for ACS and nondiagnostic initial ECG, supplemental electrocardiographic leads V7 to V9 are reasonable to rule out posterior myocardial infarction 1

Office-Based Evaluation

• For stable patients evaluated in an office setting, an ECG should be performed unless a noncardiac cause is evident 1
• If an ECG cannot be obtained in the office, transfer to the emergency department should be initiated 1
• Delayed transfer to the hospital for determination of cardiac troponin or other diagnostic testing beyond the ECG in the office setting can be detrimental and should be avoided 1

Follow-up ECGs

• Serial ECGs are indicated to evaluate response to therapy in patients with known cardiovascular disease 1
• Follow-up ECGs are warranted when:
  • Prescribed therapy is known to produce ECG changes that correlate with therapeutic responses 1
  • Medications may produce adverse effects detectable by ECG changes 1
  • New symptoms develop in patients with known cardiovascular disease 1

Preoperative Evaluation

• A preoperative ECG is recommended for all patients with known cardiovascular disease undergoing cardiac or noncardiac surgery 1

Special Considerations

Specific Cardiac Conditions

• ECG is essential for diagnosing specific patterns like Wellens syndrome (deeply inverted or biphasic T waves in precordial leads), which indicates critical stenosis of the proximal left anterior descending coronary artery 3
• ECG remains an irreplaceable first step when evaluating patients with suspected hypertrophic cardiomyopathy, as an abnormal ECG may be the only manifestation of disease at an early stage 4

ECG Interpretation Considerations

• All ECGs should be interpreted by a qualified physician, not solely by computer algorithms 1
• The ECG classification system recommended in standardized guidelines predicts 30-day composite rates of death, acute myocardial infarction, and revascularization 5

Important Pitfalls to Avoid

• Relying solely on the presence of chest pain to determine need for ECG (approximately 22% of patients with ST-elevation myocardial infarction do not present with chest pain) 2
• Failing to obtain serial ECGs when initial ECG is nondiagnostic but clinical suspicion remains high 1
• Delaying ECG acquisition beyond 10 minutes in patients with suspected ACS 1
• Overlooking the need for ECG in elderly patients with atypical presentations such as abdominal pain, nausea, or vomiting 2