When should I send an Electrocardiogram (ECG)?

When to Order an Electrocardiogram (ECG)

An ECG should be performed for all patients with suspected cardiac disease or dysfunction, those with symptoms that may indicate cardiac issues, and in patients over 40 years old before surgery. 1

Key Indications for ECG

Symptomatic Patients

• ECG should be performed for patients presenting with chest pain, dizziness, syncope, or symptoms that may predict sudden death or myocardial infarction 1
• Unless a non-cardiac cause is evident, an ECG should be performed for patients seen in office settings with stable chest pain; if unavailable, refer to the emergency department 1
• Patients with acute chest pain and suspected acute coronary syndrome should have an ECG acquired and reviewed within 10 minutes of arrival 1
• ECGs are indicated for patients with symptoms including:
  • Syncope and near-syncope 1
  • Unexplained changes in angina pattern 1
  • New or worsening dyspnea 1
  • Extreme and unexplained fatigue, weakness, or prostration 1
  • Palpitations 1

Medication Monitoring

• ECGs should be performed before and during therapy with drugs known to produce cardiac effects 1
• Common medications requiring ECG monitoring include:
  • Psychotropic agents (phenothiazines, tricyclic/tetracyclic antidepressants, lithium) 1
  • Anti-infective agents (erythromycin, pentamidine) 1
  • Antihypertensive agents (diuretics, ACE inhibitors, calcium channel and β-blockers) 1
  • Antineoplastic agents 1
  • Heart failure medications (digitalis, dopamine, dobutamine) 1
• ECGs are appropriate after initiation of drug therapy, after changes in therapy, and after addition of potentially interacting drugs 1

Preoperative Evaluation

• All patients over 40 years old should have a preoperative ECG, even without suspected cardiac disease 1, 2
• All patients with known cardiovascular disease should have a preoperative ECG before cardiac or non-cardiac surgery 1
• Patients being evaluated as donors for heart transplantation or recipients of non-cardiopulmonary transplants should have preoperative ECGs 1, 2
• Preoperative ECGs are not indicated for patients under 30 years old with no risk factors for coronary artery disease 1, 2

Follow-up Monitoring

• Patients with known cardiovascular disease should have follow-up ECGs when there are changes in symptoms, signs, or relevant laboratory findings 1
• Patients with implanted pacemakers or anti-tachycardia devices should have periodic follow-up ECGs 1
• After cardiac surgery or extensive pulmonary surgery, serial ECGs are recommended until the condition is stable and before discharge 1
• Patients undergoing cardioversion should have an ECG just before and immediately after the procedure, and before hospital discharge 1

Special Considerations

Asymptomatic Patients

• Baseline ECG is recommended for asymptomatic persons over 40 years of age 1, 2
• Some guidelines recommend a baseline ECG at age 20 years with repeats at ages 40 and 60 years 2
• In adult patients whose cardiovascular condition is usually benign and unlikely to progress, follow-up ECGs are not indicated unless changes in clinical status occur 1

High-Risk Patients

• ECGs are indicated for patients at increased risk for developing cardiac disease 1, 2
• Patients who may have received an overdose of illicit drugs known to have cardiac effects should have an ECG 1, 2

Common Pitfalls to Avoid

• Ordering "routine" ECGs without clinical indication increases healthcare costs without improving outcomes 2
• Relying solely on a normal or nonspecifically abnormal ECG in a patient with classic anginal chest pain can be dangerous 3
• Failing to compare with previous ECGs when available may result in misinterpretation of chronic findings as acute 2
• Delayed transfer to the emergency department for cardiac troponin or other diagnostic testing in patients with acute chest pain and suspected ACS should be avoided 1

Clinical Value

• In primary care, ECGs can change management in approximately 30% of cases, most commonly by preventing unnecessary specialist referrals 4
• In chest pain patients, a normal ECG significantly reduces the likelihood of cardiac events, while an abnormal ECG substantially increases this likelihood 4
• However, 1-4% of patients with completely normal ECGs and chest pain may still have acute myocardial infarction 3