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Diagnosis this
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Reading File
Here is a full breakdown of this ECG and its interpretation:
ECG Report Analysis
Patient: T. Rathna | 77-year-old Female | Acquired: 17 Jul 2026
Measured Parameters
| Parameter | Value | Normal Range |
|---|---|---|
| Atrial Rate | 60 bpm | 60-100 bpm |
| Ventricular Rate | 62 bpm | 60-100 bpm |
| QRS Duration | 126 ms | <120 ms (borderline wide) |
| QT Interval | 438 ms | varies |
| QTcB (corrected QT) | 445 ms | <440 ms F - borderline prolonged |
| PR Interval | 154 ms | 120-200 ms (normal) |
| P-R-T Axes | 56° / 18° / -44° | - |
Machine-Generated Diagnosis
Abnormal: Sinus Rhythm, Sinus Arrhythmia Seen, Complete Left Bundle Branch Block (LBBB) with Left Ventricular Hypertrophy (LVH). Please correlate clinically.
Clinical Interpretation
1. Sinus Rhythm with Sinus Arrhythmia
- P waves present, rate ~60 bpm. Sinus arrhythmia (slight variation in R-R intervals) is common and usually benign, especially in elderly patients. It can reflect normal autonomic variation.
2. Complete Left Bundle Branch Block (LBBB)
- QRS duration of 126 ms is at the threshold. Classic LBBB criteria require QRS ≥120 ms (this just meets it).
- The T-axis of -44° (discordant from QRS axis of 18°) is consistent with LBBB's characteristic secondary ST-T changes.
- On the tracing, leads V1-V3 likely show broad negative (rS or QS) complexes, and lateral leads (I, aVL, V5-V6) show broad, notched R waves - the hallmark of LBBB.
- Important: LBBB in a 77-year-old woman is NOT a normal finding. It requires investigation for:
- Coronary artery disease / prior MI
- Cardiomyopathy (dilated)
- Hypertensive heart disease
- Aortic stenosis
3. Left Ventricular Hypertrophy (LVH)
- Note: In the presence of LBBB, voltage criteria for LVH are unreliable and can be falsely positive. The machine flagging LVH alongside LBBB should be interpreted with caution.
- True LVH assessment in a patient with LBBB requires echocardiography.
4. Borderline Prolonged QTc
- QTcB of 445 ms is borderline prolonged in a female (upper limit ~440 ms). This may partly be a consequence of the LBBB itself (wide QRS artificially prolongs measured QT) rather than a primary repolarization abnormality.
Key Clinical Concern
New or unknown LBBB in a 77-year-old female is a serious finding. Per Sgarbossa criteria and clinical guidelines, new LBBB with chest pain raises concern for acute MI (STEMI-equivalent). This patient needs:
- Correlation with symptoms (chest pain, dyspnoea, syncope)
- Prior ECG comparison (is this new vs. old LBBB?)
- Troponin levels
- Echocardiogram (assess LV function, wall motion, LVH)
- Cardiology referral
Disclaimer: This interpretation is based solely on the ECG tracing and machine report. It must be correlated with the patient's clinical history, symptoms, and other investigations by a qualified medical professional. Do not make treatment decisions based on this analysis alone.
There are no symptoms
Good - that changes the clinical picture significantly. An incidentally found LBBB (no chest pain, no dyspnoea, no syncope) in an asymptomatic 77-year-old is managed differently from a symptomatic presentation.
Asymptomatic LBBB - What It Means
The LBBB itself does not require urgent intervention, but it still carries clinical significance at this age.
What Asymptomatic LBBB Tells Us
- The conduction system has disease - this is almost always organic (not a benign finding in a 77-year-old)
- The most common underlying causes are:
- Hypertensive heart disease (most common in elderly women)
- Coronary artery disease (silent/prior ischaemia)
- Age-related fibrosis of the conduction system (Lev's disease)
- Aortic valve disease (stenosis especially)
- Dilated cardiomyopathy
Prevalence Context
LBBB prevalence increases with age - found in roughly 0.5-1% of the general population but rises to ~2-3% in those over 70. It is associated with increased cardiovascular mortality even when asymptomatic.
Recommended Workup (Asymptomatic LBBB)
| Investigation | Reason |
|---|---|
| Echocardiogram (priority) | Assess LV size, EF, wall motion, valvular disease, true LVH |
| Troponin | Exclude silent myocardial injury (one-time check) |
| Compare with old ECG | Is this new or chronic? New LBBB is more significant |
| Thyroid function (TSH) | Thyroid disease can cause conduction abnormalities |
| Renal function, electrolytes | Baseline metabolic workup |
| Chest X-ray | Cardiomegaly, pulmonary congestion |
What Is NOT Needed Right Now (Asymptomatic)
- No emergency admission
- No urgent catheterisation
- No empiric antiarrhythmic drugs
- Sgarbossa / STEMI criteria are not applicable without chest pain
Bottom Line
Asymptomatic LBBB in a 77-year-old woman warrants a non-urgent but thorough cardiac workup, primarily an echocardiogram. If the echo shows preserved LV function and no significant structural disease, the patient can be monitored with periodic follow-up. If LV dysfunction is found (EF <35-40%), she may become a candidate for Cardiac Resynchronisation Therapy (CRT), which has proven benefit in symptomatic heart failure with LBBB - but that step only applies if symptoms develop.
The key message: refer to a cardiologist for outpatient workup - no emergency action needed given the absence of symptoms.
What is LBBB
Finding Sources
Finding Sources
Reading File
Here is a complete explanation of LBBB:
Left Bundle Branch Block (LBBB)
The Normal Conduction System (Background)
In a normal heart, the electrical signal travels from the SA node → AV node → His bundle → then splits into two pathways:
- Right bundle branch → activates the right ventricle
- Left bundle branch → activates the left ventricle
Both ventricles depolarise almost simultaneously, producing a narrow QRS complex (<120 ms).
What Happens in LBBB
The left bundle branch is blocked or diseased, so the electrical signal cannot travel down it normally. Instead:
- The right ventricle activates first (via the right bundle branch, normally)
- The electrical signal then spreads slowly, cell-to-cell across the septum to reach the left ventricle
- This delayed, abnormal activation of the left ventricle produces a wide, abnormal QRS complex (≥120 ms)
This causes the two ventricles to contract out of sync - called ventricular dyssynchrony - which can reduce pumping efficiency over time.
How LBBB Looks on ECG
As described in Harrison's Principles of Internal Medicine 22E, LBBB alters both early and later phases of ventricular depolarisation:
| Lead | What You See in LBBB |
|---|---|
| V1 | Broad, deep negative (QS or rS) complex |
| V6, I, aVL | Broad, tall, often notched R wave (no Q wave) |
| ST-T waves | Discordant - opposite direction to QRS |
| QRS duration | ≥120 ms (complete LBBB) |
The T-axis of -44° seen in this patient's ECG is a classic example of this discordance.
Causes of LBBB
LBBB almost always indicates underlying structural heart disease (unlike RBBB which can be benign):
- Hypertensive heart disease - most common cause, especially in elderly women
- Coronary artery disease - ischaemia damages the conduction tissue
- Dilated cardiomyopathy - stretched, diseased myocardium
- Aortic valve disease - the left bundle runs close to the aortic root
- Age-related fibrosis (Lev's disease / Lenegre's disease) - the conduction system scars with age
- Acute MI - new LBBB in the setting of chest pain is treated as a STEMI-equivalent
Why LBBB Matters
- Masking: LBBB makes it very difficult to diagnose MI on ECG because normal ST-T analysis cannot be applied - the ST changes are expected as a consequence of the block itself
- Dyssynchrony: The two ventricles contract out of sequence, which can weaken heart function over time
- Risk marker: Even asymptomatic LBBB is associated with increased cardiovascular mortality
- Treatment implications: In patients with heart failure + LBBB + reduced ejection fraction (EF <35%), Cardiac Resynchronisation Therapy (CRT) - a special pacemaker that paces both ventricles simultaneously - can restore synchrony and significantly improve outcomes (as noted in Goldman-Cecil Medicine)
Complete vs. Incomplete LBBB
| Type | QRS Duration |
|---|---|
| Complete LBBB | ≥120 ms |
| Incomplete LBBB | 110-119 ms |
This patient's QRS of 126 ms just meets the criteria for complete LBBB.
Simple Analogy
Think of the heart's electrical system like a two-lane highway. In LBBB, the left lane is blocked. Traffic (electrical signal) all has to go through the right lane first, then slowly creep over to the left side via side roads - arriving late and causing the left ventricle to contract with a delay.
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