Can you interpret an electrocardiogram (EKG)?

Can I Interpret an EKG?

Yes, you can interpret an EKG if you have completed internal medicine residency training with Advanced Cardiac Life Support (ACLS) certification, which is sufficient for bedside interpretation in routine and emergency situations. 1

Training Requirements for Competency

Initial Competency Standards

• The American College of Physicians recommends interpretation and review of 800 EKGs within a 3-year training period under supervision of experienced faculty to achieve competency. 1
• The American College of Cardiology/American Heart Association previously recommended 500 supervised EKG interpretations for initial competency, though earlier guidelines suggested 800 interpretations. 1
• These EKGs must reflect a wide variety of clinical situations and abnormalities to ensure comprehensive skill development. 1

Alternative Pathways to Competency

• Physicians who successfully pass the American Board of Internal Medicine cardiovascular subspecialty examination (including the EKG component) are considered competent in EKG interpretation. 1
• Well-designed courses coupled with structured study can provide competency for physicians outside traditional residency/fellowship pathways, though this requires verification through valid certification examinations. 1

Understanding Your Skill Level

Expected Accuracy by Training Level

• Medical students demonstrate 42.0% accuracy on pre-training assessments, residents achieve 55.8% accuracy, practicing physicians reach 68.5%, and cardiologists attain 74.9% accuracy. 2
• Even after educational interventions, physicians at all training levels show deficiencies in EKG interpretation, with median post-training accuracy of 67%. 2
• First-year internal medicine residents correctly interpret only about half of all EKGs, including critical diagnoses like complete heart block (scored 0.23/2.0). 3

Common Interpretation Errors

• Major interpretation errors occur in 4% to 33% of cases, though adverse patient outcomes from these errors are rare (less than 1% of interpretations). 1
• Noncardiologists make more EKG interpretation errors than cardiologists and are more influenced by patient history when interpreting tracings. 1
• Computer-generated interpretations contain frequent errors and must always be verified by a qualified physician—they are adjuncts only, not substitutes for physician interpretation. 1, 4, 5

Systematic Approach to Interpretation

Rate and Rhythm Assessment

• Calculate heart rate by counting QRS complexes in a 6-second strip and multiplying by 10, or use 300 divided by the number of large boxes between consecutive R waves. 4, 5
• Identify the underlying rhythm by confirming a P wave before each QRS complex with consistent PR interval for sinus rhythm (normal: 60-100 bpm). 4, 5
• Evaluate rhythm regularity by examining R-R intervals for consistency. 4

Interval Measurements

• Measure PR interval (normal: 120-200 ms or 3-5 small squares) to assess AV conduction. 4, 5
• Evaluate QRS duration (normal: <120 ms or <3 small squares) to identify ventricular conduction delays. 4, 5
• Calculate corrected QT interval (QTc) using Bazett's formula; normal <450 ms for men, <460 ms for women. 4, 5

Axis Determination

• Examine leads I and aVF to quickly determine axis quadrant: normal axis when both are positive (+90° to -30°). 4, 5
• Left axis deviation shows positive lead I and negative aVF (-30° to -90°). 4, 5
• Right axis deviation shows negative lead I and positive aVF (+90° to +180°). 4, 5

Waveform Analysis

• Examine P wave morphology (normal: upright in I, II, aVF; biphasic in V1) to assess atrial conduction. 4
• Analyze QRS complexes for pathologic Q waves (>1 mm wide and >1/3 the height of R wave or >0.04 seconds or >25% of R wave amplitude) suggesting myocardial infarction. 4, 5
• Assess ST segments for elevation (>0.1 mV in limb leads or >0.15-0.2 mV in precordial leads) indicating acute injury requiring emergent intervention. 5, 6

Critical Clinical Integration

Never Interpret in Isolation

• Always interpret the EKG in context of the patient's clinical presentation—the same EKG pattern may occur in different pathophysiologic states with vastly different implications. 5, 6
• Clinical signs and symptoms alone have insufficient sensitivity (35-38%) and specificity (28-91%) to rule in or rule out acute coronary syndrome without EKG and biomarkers. 6
• Compare with previous tracings when available, as failure to do so can miss important dynamic changes. 5, 6

Technical Quality Verification

• Verify proper electrode placement and adequate filtering settings before interpretation, as misplaced precordial leads significantly alter findings and lead to false diagnoses. 5, 6
• Ensure minimum high-frequency response of 150 Hz for adults and 250 Hz for children to maintain diagnostic precision. 5, 6
• Evaluate recording quality by checking for artifacts, electrical interference, and baseline stability. 5

Maintaining Competency

Ongoing Requirements

• The American College of Cardiology/American Heart Association recommends reading 100 EKGs yearly to maintain competency. 1
• Continuing medical education through seminars or self-assessment programs is essential for physicians who read EKGs infrequently to keep skills current. 5, 6
• Periodic self-study or continuing education ensures skills remain current, particularly given the wide variation in interpretation accuracy even among experienced physicians. 5

Common Pitfalls to Avoid

• Do not over-rely on computer interpretation without physician verification—automated systems still produce frequent errors, particularly with arrhythmias. 1, 5
• Do not fail to consider technical factors like electrode placement and filtering, which can significantly affect EKG appearance and interpretation. 4, 5
• Do not interpret findings without clinical context, which may lead to inappropriate management decisions and adverse patient outcomes. 5, 6
• Recognize that interpretation varies greatly even among expert electrocardiographers, underscoring the need for systematic approach and ongoing education. 5