ECG Analysis - Mubeena, 48F | 28 Jun 2026

Patient & Recording Details

Systematic Interpretation

• Heart rate is 124 bpm - this is sinus tachycardia
• P waves are present, upright in leads I, II, aVF and inverted in aVR - confirming normal sinus origin
• Rhythm appears regular

• P-axis: 49° (normal)
• QRS-axis: 89° (normal, borderline towards vertical/right)
• T-axis: 26° (normal)

• Normal morphology and polarity
• Upright in II, III, aVF; inverted in aVR - consistent with normal sinus rhythm

• Normal (120-200 ms range) - no first-degree AV block

• Narrow - no bundle branch block or intraventricular conduction delay
• Normal R-wave progression in precordial leads (transition around V3/V4)
• No pathological Q waves noted

• QTc = 434 ms - this is borderline prolonged (normal upper limit for females is ~450 ms, but values >430 ms warrant attention in the clinical context)
• Important note: At a rate of 124 bpm, the Bazett formula tends to over-correct and can artificially inflate QTc - this is a known limitation
• Clinical significance should be assessed in context (medications, electrolytes)

• No obvious ST elevation or depression noted on visual review
• T waves appear normal in morphology
• No features of acute ischemia or injury pattern visible

Summary Interpretation

Sinus Tachycardia at 124 bpm with borderline QTc (434 ms) No acute ischemic changes, no bundle branch block, no significant axis deviation.

Clinical Considerations

• Per the Clozapine Handbook (textbook library): "Tachycardia is often associated with QT prolongation due to the persistent use of the Bazett rate correction formula... this formula was derived in 1920 from 39 subjects" - meaning at rate 124, the true QTc may actually be lower
• Female threshold for concern is typically QTc >450 ms; 434 ms is within acceptable range but worth monitoring if on QT-prolonging drugs

Recommended Next Steps

1. Identify the cause of tachycardia - clinical history, vitals, symptoms
2. Check electrolytes (K⁺, Mg²⁺, Ca²⁺) if QTc concern
3. Review medications for QT-prolonging drugs
4. Repeat ECG once heart rate normalizes to accurately reassess QTc
5. Consider thyroid function tests, CBC (for anemia), and clinical correlation

⚠️ Disclaimer: This ECG analysis is for educational/clinical decision support purposes only. All interpretations must be correlated with the patient's clinical presentation and confirmed by a qualified physician.