ECG Interpretation — Bimal Kumar Padhe, Male, 60 Years

Measured Parameters

Machine Diagnosis (Confirmed)

1. Sinus Rhythm — Normal sinus P waves at 86 bpm
2. First-Degree Atrioventricular Block — PR interval of 222 ms (>200 ms)
3. Complete Left Bundle Branch Block (CLBBB) — QRS duration of 161 ms (>120 ms)

ECG Feature Analysis

• Regular P waves preceding every QRS, rate 86 bpm — normal sinus origin confirmed.

• PR interval 222 ms indicates delayed conduction through the AV node, but every P wave still conducts. This is a benign conduction delay on its own but gains significance in the context of LBBB (see below).

• QRS ≥120 ms (161 ms here — markedly prolonged)
• Broad, monophasic (notched/M-shaped) R waves in lateral leads I, aVL, V5, V6
• Deep, wide S waves / QS pattern in right precordial leads V1–V3 (predominantly negative deflections)
• Secondary ST-T wave changes (discordant): ST depression + T-wave inversion in lateral leads (I, aVL, V5–V6); ST elevation in V1–V3 — this is expected with LBBB and does NOT necessarily indicate acute ischemia on its own
• QTc 452 ms — mildly prolonged, secondary to the wide QRS of LBBB (expected)

Clinical Significance

• Ischemic heart disease / Coronary artery disease (most common cause in this age group)
• Hypertensive heart disease / Left ventricular hypertrophy
• Dilated cardiomyopathy
• Fibrosis of the conduction system (Lenegre–Lev disease)

As highlighted in Pfenninger & Fowler's Procedures for Primary Care: LBBB "is quite ominous in an older population as a marker for an increased risk of death, stroke, and CHF." In a patient with LBBB presenting with prolonged chest pain, STEMI must be ruled out — Sgarbossa criteria or modified Sgarbossa criteria should be applied.

Key Action Points

1. Correlate clinically — is the patient symptomatic (chest pain, dyspnea, syncope, palpitations)?
2. Compare with prior ECGs — new LBBB is a medical emergency until proven otherwise
3. Echocardiogram — assess LV size, function, wall motion abnormalities
4. Cardiac biomarkers (Troponin) — to exclude acute MI
5. If chest pain is present → treat as STEMI equivalent; apply Sgarbossa criteria
6. Consider Holter monitoring given the bifascicular-level conduction disease (LBBB + 1° AV block)

Management of CLBBB + First-Degree AV Block

Step 1 — Immediate Assessment (Emergency Triage)

Step 2 — Immediate Investigations (Mandatory)

Step 3 — Treat the Underlying Cause

A. Ischemic Heart Disease (most likely in a 60-year-old male)

• Anti-platelet therapy: Aspirin 75–150 mg/day ± Clopidogrel
• Statin: Atorvastatin 40–80 mg at night
• ACE inhibitor/ARB: Ramipril or Perindopril (LVEF protection)
• Beta-blocker: Carvedilol or Bisoprolol (reduces sudden death risk)
• Coronary angiography if troponin positive or stress test positive

B. Heart Failure with Reduced EF (HFrEF — if LVEF ≤40%)

• ACE-I/ARB/ARNI (Sacubitril-Valsartan preferred if tolerated)
• Beta-blocker (Carvedilol, Bisoprolol, or Metoprolol succinate)
• MRA (Spironolactone/Eplerenone)
• SGLT2 inhibitor (Dapagliflozin or Empagliflozin — proven mortality benefit)

C. Hypertensive Heart Disease

• Optimise BP control: target <130/80 mmHg
• Preferred agents: ACE-I/ARB + amlodipine ± thiazide diuretic

Step 4 — Device Therapy (If LVEF ≤35%)

Cardiac Resynchronization Therapy (CRT)

• LVEF ≤35%
• LBBB pattern on ECG ✓ (this patient has this)
• QRS ≥120 ms ✓ (this patient: 161 ms)
• Sinus rhythm ✓ (this patient has this)
• NYHA class II–IV symptoms despite optimal medical therapy

CRT reduces all-cause mortality by 24–36% (COMPANION and CARE-HF trials). Most benefit accrues when QRS >149 ms with LBBB pattern — this patient (QRS 161 ms) sits squarely in the highest-benefit zone.

CRT-D (CRT + ICD) — Consider if:

• LVEF <35% + NYHA II–III → ICD component adds SCD prevention
• Particularly beneficial in ischemic cardiomyopathy

Step 5 — First-Degree AV Block

• Holter monitor — to detect higher-degree block (2° or 3° AV block) intermittently
• Electrophysiology (EP) study — if syncope or presyncope occurs; assess His-Purkinje conduction (HV interval >70 ms indicates high risk for progression to complete heart block)
• Permanent pacemaker — if EP study shows markedly prolonged HV interval or spontaneous high-degree block develops

Step 6 — Lifestyle & Secondary Prevention

• Smoking cessation
• Sodium restriction (<2 g/day if HF present)
• Fluid restriction if symptomatic HF
• Regular moderate exercise (cardiac rehab if post-MI or HF)
• Annual influenza + pneumococcal vaccination

Summary Algorithm

CLBBB + 1° AVB in 60M
         ↓
Rule out ACS (Troponin + symptoms)
         ↓
Echocardiogram → LVEF?
    ↓              ↓
LVEF >40%       LVEF ≤35%
(No HF)         ↓
    ↓        Optimise medical Rx (GDMT)
Treat cause     ↓
(IHD/HTN)   CRT-D if NYHA II-IV + QRS ≥120ms LBBB
    ↓
Holter for progression to higher-degree block