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

ECG Procedure and Management of Abnormal Results

Proper Procedure for Obtaining an ECG

A standard 12-lead ECG should be performed with proper electrode placement and must be interpreted by a qualified physician, not by automated computer analysis alone, to be considered a valid diagnostic test. 1

Technical Requirements

• Standard 12-lead configuration with rhythm strip or special leads as clinically indicated 1
• Automated report followed by expert physician review if the automated interpretation identifies possible abnormalities 1
• Patient should receive a copy of both the ECG and the interpretation report 1
• Comparison with previous ECGs is essential when available to distinguish chronic from acute findings 2

Key Indications for ECG

• Cardiac symptoms: chest pain, syncope, near-syncope, palpitations, new or worsening dyspnea, or unexplained extreme fatigue 1
• Preoperative evaluation: all patients over 40 years with known cardiovascular disease 2
• Medication monitoring: drugs with cardiovascular effects (antiarrhythmics, psychotropics, chemotherapy agents, diuretics) 1, 2
• Suspected cardiac disease: based on physical examination findings, family history, or other laboratory abnormalities 1

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Management of Abnormal ECG Results

Initial Evaluation Framework

All abnormal ECG findings require evaluation under the direction of a cardiologist, with the extent of additional testing guided by initial findings, clinical suspicion, symptoms, and family history of inherited cardiac disease or sudden cardiac death. 1

Specific Abnormalities and Next Steps

T-Wave Abnormalities

• Abnormal T-wave inversion (≥1 mm depth in ≥2 contiguous leads, excluding aVR, III, V1) requires:
  • Echocardiography 1
  • Consider cardiovascular magnetic resonance (CMR) 1
  • Exercise ECG testing 1
  • Evaluation for hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), or arrhythmogenic right ventricular cardiomyopathy (ARVC) 1

ST-Segment Depression

• Horizontal or downsloping ST depression ≥0.5 mm suggests:
  • Echocardiography as first-line imaging 1
  • Exercise ECG or pharmacologic stress testing 1
  • CMR or CT coronary angiography if stress testing unavailable 1
  • Evaluation for coronary artery disease or cardiomyopathy 1

Pathological Q Waves

• Q waves ≥0.04 seconds or ≥25% of R wave height require:
  • Echocardiography 1
  • CMR imaging 1
  • Assessment for prior myocardial infarction 1

Ventricular Arrhythmias

• Multiple premature ventricular contractions (PVCs), couplets, triplets, or non-sustained ventricular tachycardia mandate:
  • Echocardiography 1
  • CMR imaging 1
  • Minimum 24-hour Holter monitoring 1
  • Exercise ECG testing 1
  • If >2,000 PVCs detected, comprehensive cardiac testing including CMR is warranted 1

Conduction Abnormalities

• Advanced second-degree or third-degree AV block:

  • Echocardiography 1
  • Minimum 24-hour ECG monitoring 1
  • Exercise ECG testing 1
  • Consider laboratory screening and CMR based on echo findings 1

• Profound first-degree AV block (≥400 ms) or profound sinus bradycardia (<30 bpm):

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

QT Interval Prolongation

• Prolonged QTc requires:
  • Repeat resting ECG on separate day 1
  • Exercise ECG testing 1
  • Electrolyte screening 1
  • Family screening and genetic testing when clinical suspicion is high 1
  • Direct referral to heart rhythm specialist if QTc ≥500 ms 1

Brugada Type 1 Pattern

• Immediate referral to cardiologist or heart rhythm specialist 1
• High precordial lead ECG with V1-V2 in second intercostal space 1
• Consider sodium channel blockade if pattern is indeterminate 1
• Genetic testing and family screening 1

Ventricular Pre-excitation (WPW Pattern)

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

Atrial Tachyarrhythmias

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

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Critical Management Principles

Activity Restriction

Temporary restriction from athletic activity should be considered for athletes with abnormal ECGs of uncertain clinical significance until secondary investigations are completed. 1

Monitoring Strategy

• Holter monitoring has limited yield in syncope evaluation (only 4% symptom-ECG correlation in unselected populations) 1
• Implantable loop recorders should be considered for infrequent syncope recurring over months to years 1
• Serial ECGs are warranted until disease process and response to therapy have stabilized 1

Common Pitfalls to Avoid

• Do not rely on automated computer interpretation alone—physician review is mandatory 1
• Avoid ordering routine ECGs without clinical indication, as this increases costs without improving outcomes 2
• Do not perform tilt-table testing for uncomplicated vasovagal syncope diagnosed by history alone 1
• Do not request electroencephalography for brief seizure activity during clear syncope, as this may lead to misdiagnosis 1