ECG Diagnosis Cannot Be Made Without Viewing the Actual ECG
You must provide the actual ECG tracing or describe specific ECG findings for me to make a diagnosis. An ECG diagnosis requires systematic analysis of the actual waveforms, intervals, and morphologies present on the recording.
Systematic Approach to ECG Interpretation
When you provide the ECG, I will analyze it using this algorithmic framework 1:
Step 1: Rate and Rhythm Assessment
- Calculate heart rate (normal: 60-100 bpm)
- Identify rhythm (sinus vs. non-sinus)
- Assess regularity and presence of ectopy
Step 2: Interval Measurements
- PR interval (normal: 120-200 ms) - identifies AV conduction abnormalities
- QRS duration (normal: <120 ms) - distinguishes narrow vs. wide complex rhythms
- QT/QTc interval - assesses repolarization abnormalities
Step 3: Axis Determination
- QRS axis (normal: -30° to +90°)
- Identifies chamber enlargement or conduction blocks
Step 4: Morphology Analysis
For Wide QRS Complexes (>120 ms): The differential diagnosis includes three main categories 2:
- Ventricular pre-excitation (WPW pattern)
- Aberrant conduction (bundle branch blocks)
- Ventricular beats (PVCs, ventricular tachycardia)
For ST Segment Changes: Critical for acute coronary syndrome diagnosis 3, 4, 5:
- ST elevation in contiguous leads with active symptoms → acute coronary occlusion requiring emergent reperfusion
- ST depression in V1-V3 → posterior wall STEMI equivalent
- Widespread ST depression with aVR elevation → left main or severe three-vessel disease
- Up-sloping ST depression with positive T waves → severe LAD obstruction
Step 5: Wave Morphology
- Q waves: QS morphology or pathologic Q waves (>40 ms duration, >25% R wave amplitude) suggest prior infarction 6
- R wave progression: Poor progression in precordial leads suggests anterior pathology
- T wave changes: Hyperacute T waves, inversions, or symmetric changes indicate ischemia
Critical Pitfalls to Avoid
Context is essential - The same ECG finding has different implications based on:
- Presence or absence of active symptoms 4, 5
- Comparison with prior ECGs
- Clinical presentation and hemodynamic status
Common false positives:
- ST elevation from early repolarization, pericarditis, or LVH rather than STEMI
- Tachycardia can falsely suggest LVH due to shortened diastolic filling 7
- QS complexes from hypertrophic cardiomyopathy mimicking old infarction 6
High-risk patterns requiring urgent action 5:
- ST elevation meeting STEMI criteria with symptoms
- New or presumably new LBBB with symptoms
- Widespread ST depression with aVR elevation
- Hemodynamic instability with any ischemic pattern
What I Need From You
To provide a specific diagnosis, describe or provide:
- The actual ECG image, or
- Detailed findings: rate, rhythm, intervals, axis, ST-T changes, Q waves, R wave progression, and any other abnormalities
- Clinical context: symptoms, hemodynamic status, prior ECGs
The ECG must be interpreted alongside clinical data - it records global cardiac electrical activity, not just local events under specific electrodes 3. Lead placement and technical factors affect interpretation 1.