What is the proper procedure for getting an electrocardiogram (ECG) and what are the potential next steps if an abnormal result is found?

Proper ECG Procedure and Management of Abnormal Results

A standard 12-lead ECG should be performed with proper lead placement and interpreted by a qualified physician, not by automated computer analysis alone, and any abnormal findings require systematic evaluation based on the specific abnormality detected. 1

ECG Acquisition Standards

The ECG must meet specific technical requirements to be clinically useful:

• All 12 standard leads must be recorded with proper electrode placement to ensure accurate electrical activity capture 1
• Automated computer interpretation alone is insufficient – a physician qualified in ECG interpretation must review and sign off on the tracing 1
• The interpreted ECG must become part of the permanent medical record, and patients should receive a copy of both the ECG and the interpretation report 1
• Current tracings should always be compared with previous ECGs when available to distinguish chronic findings from acute changes 2

When to Order an ECG

Class I Indications (Essential)

• Patients presenting with cardiac symptoms: chest pain, syncope, near-syncope, palpitations, new or worsening dyspnea, or extreme unexplained fatigue 1
• Known cardiovascular disease or dysfunction requiring baseline or follow-up assessment 1
• Preoperative evaluation in patients over 40 years old, even without suspected cardiac disease 2
• Before initiating medications with known cardiac effects: antiarrhythmic drugs, psychotropic agents (phenothiazines, tricyclic antidepressants, lithium), antineoplastic agents, or medications affecting electrolytes 1, 2
• Suspected drug overdose with agents known to have cardiac effects 1

Class II Indications (Reasonable)

• Baseline ECG for asymptomatic persons over 40 years of age 2
• Periodic follow-up (every 1-5 years) for patients at increased risk for developing cardiac disease 1, 2

Class III Indications (Not Recommended)

• Routine screening in asymptomatic patients under 30 years old without risk factors for coronary artery disease 2
• Repeat ECGs without clinical indication – this increases healthcare costs without improving outcomes 2

Systematic Approach to Abnormal ECG Findings

When an abnormality is detected, the evaluation pathway depends on the specific finding. Initial evaluation of ECG abnormalities should be performed under the direction of a cardiologist. 1

Critical Abnormalities Requiring Urgent Referral

Advanced 2nd or 3rd degree atrioventricular block:

• Immediate echocardiography 1
• Minimum 24-hour ECG monitoring 1
• Exercise ECG testing 1
• Consider laboratory screening and cardiac MRI based on echocardiography findings 1

Ventricular arrhythmias (couplets, triplets, accelerated ventricular rhythm, non-sustained ventricular tachycardia):

• Comprehensive cardiac evaluation including echocardiography, cardiac MRI, minimum 24-hour ECG monitor, and exercise ECG testing to rule out myocardial disease and primary electrical disease 1

Brugada Type 1 pattern:

• Direct referral to cardiologist or heart rhythm specialist 1
• Consider high precordial lead ECG with leads V1 and V2 in 2nd intercostal space 1
• Genetic testing and family screening 1

Significant Abnormalities Requiring Cardiology Evaluation

Abnormal T-wave inversion (≥1 mm depth in two or more contiguous leads):

• Echocardiography as first-line imaging 1
• Exercise ECG testing 1
• Consider cardiac MRI if echocardiography suggests structural disease 1
• Exception: TWI confined to leads V1-V4 in Black athletes with J-point/ST elevation, or V1-V3 in athletes <16 years old is considered normal 1

Prolonged QTc interval:

• Repeat resting ECG on a separate day to confirm 1
• Exercise ECG testing 1
• Laboratory screening for electrolyte abnormalities 1
• Family screening and genetic testing when clinical suspicion is high 1
• Direct referral to heart rhythm specialist for QTc ≥500 ms 1

Multiple premature ventricular contractions:

• Echocardiography 1
• If >2,000 PVCs or non-sustained ventricular tachycardia present, comprehensive cardiac testing including cardiac MRI is warranted 1
• 24-hour ECG monitoring 1
• Exercise ECG testing 1

Ventricular pre-excitation (Wolff-Parkinson-White pattern):

• Exercise ECG testing to assess pathway risk 1
• Abrupt cessation of delta wave on exercise ECG indicates low-risk pathway 1
• Consider electrophysiology study for risk assessment if low-risk pathway cannot be confirmed non-invasively, especially for moderate to high-intensity sports participation 1

Atrial tachyarrhythmias:

• Echocardiography 1
• Minimum 24-hour ECG monitoring 1
• Exercise ECG testing 1
• Consider cardiac MRI or electrophysiology study based on clinical suspicion 1

Moderate Abnormalities

Profound sinus bradycardia (<30 beats/min) or profound 1st degree AV block (≥400 ms):

• Repeat ECG after mild aerobic activity 1
• Additional testing based on clinical suspicion 1

Two or more borderline ECG findings:

• Echocardiography 1
• Additional testing based on clinical suspicion 1

Serial ECG Monitoring Indications

Repeat ECGs are warranted in specific clinical scenarios:

• Acute ischemia or myocardial infarction: Serial ECGs to assess response to thrombolytic or anti-ischemic therapy 1
• Post-coronary angioplasty or intracardiac procedures: Serial ECGs until stable, then before hospital discharge 1
• Initiation of antiarrhythmic drugs: To assess rhythm conversion, QRS duration, QT prolongation, or proarrhythmia 1
• Cardioversion procedures: ECG immediately before, immediately after, and before hospital discharge 1
• Pacemaker insertion or revision: ECG soon after procedure, when malfunction suspected, after lead threshold maturation, and at periodic intervals 1

Common Pitfalls to Avoid

• Relying solely on automated computer interpretation can lead to significant diagnostic errors 1, 2
• Failing to obtain old ECGs for comparison may result in misinterpreting chronic findings as acute pathology 2
• Ordering routine ECGs without clinical indication wastes resources and may lead to unnecessary downstream testing 2
• Misinterpreting brief seizure activity during vasovagal syncope as epilepsy – when history clearly indicates syncope, this does not require neurologic investigation 1
• Performing tilt-table testing for uncomplicated vasovagal syncope when clinical history is typical (the "3 Ps": posture, provoking factors, prodromal symptoms) 1

Role in Specific Populations

Athletes:

• Abnormal ECG findings in athletes always require further assessment to exclude intrinsic cardiac disease 1
• Temporary restriction from athletic activity should be considered until secondary investigations are completed for abnormal ECGs of uncertain significance 1

Patients with transient loss of consciousness:

• 12-lead ECG is an essential, integral part of initial assessment 1
• Automated report with subsequent expert review if abnormality identified 1