Can you interpret an electrocardiogram (ECG)?

ECG Interpretation by Qualified Physicians

ECGs must always be interpreted by qualified physicians with formal training, as computer algorithms have significant limitations with error rates up to 75% for certain conditions, and incorrect interpretations can significantly impact patient morbidity and mortality. 1

Qualifications and Competency Requirements

• A qualified physician interpreter should have:

  • Formal training in ECG interpretation during residency or fellowship
  • Understanding of cardiac electrophysiology and pathophysiology
  • Experience relating ECG findings to clinical context
  • Ability to identify technical artifacts 1

• Competency development requires:

  • Interpreting 500-800 ECGs under supervision 1
  • Regular practice (at least 100 ECGs yearly) to maintain proficiency 1
  • Residency training in internal medicine with Advanced Cardiac Life Support instruction is considered sufficient for bedside interpretation in routine and emergency situations 2, 1

Limitations of Computer Interpretation

• Computer ECG analysis should only be used as an adjunct to physician interpretation, not a replacement 2
• Only 0-94% of disorders are correctly classified by computer algorithms, with arrhythmias being particularly problematic 2, 1
• Error rates are significant: 40.7% for acute myocardial infarction and 75% for high-degree AV blocks 1

Systematic Approach to ECG Interpretation

A qualified physician should follow a systematic approach:

1. Verify technical quality:

   • Check lead placement and recording quality
   • Confirm calibration (standard: 10 mm/mV, 25 mm/s)
   • Ensure adequate bandwidth (≥150 Hz for adults, ≥250 Hz for children) 1

2. Analyze key components:

   • Rate: Normal sinus rhythm (60-100 bpm), bradycardia (<60 bpm), tachycardia (>100 bpm)
   • Rhythm: Regular vs. irregular
   • Intervals: PR (120-200 ms), QRS (<120 ms), QT/QTc (<450 ms in men, <460 ms in women)
   • Axis: Normal vs. deviation
   • Chamber abnormalities: Hypertrophy, enlargement
   • ST-T changes: Ischemia, infarction, repolarization abnormalities 1

3. Integrate with clinical context:

   • ECG findings must be interpreted in light of the patient's clinical situation
   • Previous ECGs should be compared when available 1

Common Pitfalls in ECG Interpretation

• Major interpretation errors are common (4-33%) even among trained physicians 2, 1
• Misplacement of electrodes (especially V1/V2 placed too high) can lead to inaccurate interpretations 1
• Over-reliance on computer interpretation without physician verification 1
• Failure to consider clinical context when interpreting findings 1

Maintaining ECG Interpretation Skills

• Continuing medical education through seminars or self-assessment programs is encouraged, especially for physicians who read ECGs infrequently 2
• Periodic objective assessment of interpretation skills in clinical context is more important than completing a minimum number of interpretations 1
• Online learning modules have shown effectiveness in improving ECG interpretation skills, with studies showing 18.2% absolute increase in accuracy after module completion 3

Current State of ECG Interpretation Accuracy

• Accuracy varies widely by training level: 42% for medical students, 55.8% for residents, 68.5% for practicing physicians, and 74.9% for cardiologists 4
• Even after educational interventions, deficiencies in ECG interpretation persist across all training levels 4
• Web-based learning offers a promising approach to improving ECG interpretation skills 5, with perceptual and adaptive learning modules showing significant improvements in both accuracy and fluency of ECG interpretation 6