ECG Interpretation

Machine Measurements (from printout)

Key Findings

1. Rhythm

2. First-Degree AV Block

3. Complete Left Bundle Branch Block (LBBB) - PRIMARY DIAGNOSIS

• V1-V3: Deep, wide QS/rS pattern (negative deflections)
• V4-V6: Broad, notched, slurred monophasic R-waves with absent septal Q-waves
• This is diagnostic of complete LBBB

4. Secondary ST-T Changes (expected in LBBB)

• V1-V3: ST elevation + upright T waves (concordant with negative QRS - appropriate discordance)
• V4-V6: ST depression + T-wave inversion (concordant with positive QRS - appropriate discordance)

5. Prolonged P Duration (160 ms)

Clinical Significance

• Clinical symptoms - chest pain, dyspnea, syncope, presyncope
• Troponin levels - to rule out acute MI (LBBB can mask ST-elevation MI)
• Previous ECGs - Is this new or old? A new LBBB in the context of chest pain meets STEMI-equivalent criteria under modified Sgarbossa criteria
• Echo - to assess LV function and structural disease (cardiomyopathy, etc.)

• Ischemic heart disease / acute MI
• Dilated cardiomyopathy
• Hypertensive heart disease
• Aortic valve disease
• After cardiac intervention/pacemaker
• Rarely, normal variant in older adults

Disclaimer: This is an AI-assisted interpretation for reference only. All clinical decisions must be made by a qualified physician correlating this ECG with the patient's full clinical picture.

Sgarbossa Criteria Applied to This ECG

Background

Original Sgarbossa Criteria (Score-Based)

A score ≥3 is considered positive. This ECG meets the threshold (score = 5).

Modified Sgarbossa Criteria (Smith 2012 - ST/S Ratio)

The modified criteria are POSITIVE in V2 and V3 (ratio ≥0.25).

Limb Leads Summary

• Lead I, II, aVL: Isoelectric ST - no concordant changes. Negative.
• Lead III, aVF: Mild discordant ST elevation ~1.5-2mm - within expected LBBB range. Negative.
• aVR: Mild discordant elevation ~0.5-1mm. Negative.

Interpretation

• Criterion 1 (original): Concordant ST elevation in V4-V5 is the most specific sign of acute anterior MI in LBBB (specificity ~94%)
• Modified ratio: V2 and V3 both at the 0.25 threshold suggests the discordant ST elevations in the anterior leads are disproportionate to the S-wave depth

Clinical Bottom Line

This ECG in a patient with LBBB meets Sgarbossa criteria for possible STEMI-equivalent (anterior/anterolateral territory). This requires immediate clinical correlation - troponins, symptoms, prior ECG comparison. If new LBBB with chest pain + positive Sgarbossa, this should be managed as a STEMI-equivalent with urgent cardiology review and consideration for primary PCI.

Decision Framework: Should You Give Thrombolysis?

Step 1 - Does This ECG Qualify for Reperfusion?

• Positive original Sgarbossa score (5/10 - above threshold of 3)
• Positive modified Sgarbossa ratio in V2 and V3 (both = 0.25)
• First-degree AV block (PR 238ms) suggesting additional conduction disease

Step 2 - PCI vs Thrombolysis: The Priority Decision

Per Goldman-Cecil Medicine: Primary PCI is "a preferred reperfusion strategy for ST-segment elevation or LBBB acute MI within 12 hours of symptom onset."

Step 3 - Give Thrombolysis ONLY If:

1. PCI is NOT available within 120 minutes (door-to-balloon time)
2. Symptom onset within 12 hours (best within 6 hours)
3. No absolute contraindications (see below)
4. Patient has symptoms consistent with ACS (chest pain, dyspnea, diaphoresis)
5. This LBBB is new or presumably new (no prior ECG showing LBBB)

Absolute Contraindications to Thrombolysis

Relative Contraindications (Weigh Risk vs. Benefit)

• Major surgery within 3 weeks
• Recent internal bleeding (2-4 weeks)
• Active peptic ulcer
• Prolonged CPR (>10 min)
• BP 175-200 mmHg on admission
• Age >75 (higher hemorrhagic stroke risk)
• Pregnancy
• Current anticoagulation use

Critical Questions You Must Answer Before Deciding

1. Is PCI available within 120 minutes? - If YES, transfer immediately, do not lyse.
2. When did symptoms start? - If >12 hours with no ongoing symptoms, reperfusion benefit is lost.
3. Is this LBBB new? - Without a prior ECG to compare, you must treat it as "presumably new."
4. Does the patient have ischemic symptoms? - Sgarbossa-positive ECG + symptoms = act.
5. Any contraindications present? - Screen all absolute/relative contraindications.

Bottom Line Answer

If PCI is available within 120 min: Transfer now - do NOT give thrombolytics. This is a STEMI-equivalent with positive Sgarbossa criteria.

If PCI is NOT available within 120 min AND symptom onset <12 hours AND no contraindications: Give thrombolysis. This ECG meets criteria (positive Sgarbossa + new/presumably new LBBB + clinical context required).

Do NOT lyse blindly on the ECG alone - you must confirm: active symptoms, new LBBB, no contraindications, and PCI unavailability.

✅ Go / No-Go for Thrombolysis

Can the patient reach PCI within 120 minutes of first medical contact?

• YES → Transfer immediately. Do NOT lyse. PCI is superior.
• NO → Give thrombolysis now. Every 30 minutes of delay = lives lost.

Immediate Pre-Thrombolysis Checklist (do simultaneously)

Thrombolytic Agent - Choose One

Option 1: Tenecteplase (TNK-tPA) - PREFERRED

Option 2: Alteplase (t-PA) - Accelerated regimen

• 15 mg IV bolus, then
• 0.75 mg/kg over 30 min (max 50 mg), then
• 0.5 mg/kg over 60 min (max 35 mg)
• Total max dose: 100 mg

Option 3: Streptokinase - Cheapest, widely available

• 250,000 units IV loading over 30 minutes, then
• 100,000 units/hour for 24 hours
• Watch for allergic reactions (fever, hypotension)
• Avoid if prior streptokinase use (antibody resistance)
• Do NOT use if prior streptokinase within 5 years

Post-Thrombolysis Monitoring (first 90 minutes)

• ST elevation resolves by >50% in the worst lead
• Pain relief
• Reperfusion arrhythmia (accelerated idioventricular rhythm - benign, do NOT treat)
• Peak troponin washout earlier than expected

• Persistent ST elevation
• Ongoing chest pain
• Hemodynamic instability

Watch For - Bleeding Complications

• Neurological deterioration = intracranial hemorrhage → STOP infusion immediately, reverse
• Access site oozing = compress
• Avoid unnecessary venepunctures and arterial lines after lysis

Bottom line: If PCI is not reachable in time - YES, give thrombolysis. Positive Sgarbossa + active chest pain + new LBBB = clear indication. Start aspirin + clopidogrel now, give TNK as a single bolus (weight-based), start heparin infusion, monitor for reperfusion, and arrange transfer for angiography within 24 hours.

Post-Thrombolysis ECG Analysis

Key Question: Did Thrombolysis Work?

Critical Reperfusion Assessment at 60-90 Minutes

⚠️ This Pattern = FAILED THROMBOLYSIS

• LBBB persists (QRS 174ms unchanged)
• Persistent concordant ST elevation in V4-V5 (Sgarbossa Criterion 1 still positive)
• No reperfusion arrhythmias
• No ST resolution
• Hyperacute T-waves remain in V1-V4

🚨 ACTION REQUIRED: RESCUE PCI

Per Rosen's Emergency Medicine: "Rescue PCI has not been associated with improved short-term or long-term survival... however, the incidence of heart failure and recurrent infarction was reduced. Although controversial, evidence favors rescue PCI (Class IIa recommendation)."

Immediate Steps:

1. Ask the patient: Is the chest pain still present or worsening?
   • Pain ongoing → Failed reperfusion confirmed → Rescue PCI urgently
   • Pain resolved → Reassess ST segments at 90 min - if >50% resolution, may be partial success
2. Call the cath lab / transfer NOW - do not wait for 90-minute mark if:
   • Ongoing chest pain
   • Persistent ST elevation
   • Hemodynamic deterioration (cardiogenic shock developing)
   • Malignant arrhythmia
3. Do NOT re-lyse - repeat thrombolysis is NOT recommended (no mortality benefit, increased bleeding risk)
4. Continue heparin infusion - keep anticoagulated for transfer
5. Monitor for:
   • Cardiogenic shock (BP, urine output, mental status)
   • VF/VT - have defibrillator ready
   • Complete heart block (LBBB + 1st degree AVB = risk of complete AVB)

Complete Heart Block Risk ⚠️

Current Situation Summary

• New LBBB + First-degree AV block (PR 238ms)
• Positive Sgarbossa criteria (concordant ST elevation V4-V5, modified ratio positive V2-V3)
• Active chest pain
• Decision made: thrombolysis indicated (assuming PCI not reachable in time)

What You Need to Do Right Now

1. Give Thrombolysis (if not already given)

• Aspirin 300mg chew + Clopidogrel 300mg PO - now
• Tenecteplase single IV bolus (weight-based: 30-50mg)
• Start UFH infusion after bolus

2. Set a 90-Minute Timer from Lytic Administration

3. At 90 Minutes - Do Repeat ECG

• ST resolution >50% in the lead with maximum elevation = success
• LBBB resolution = strong reperfusion sign
• AIVR = reperfusion arrhythmia (good sign, do not treat)
• Persistent changes = failed lysis → Rescue PCI

4. Watch Continuously For

Is This a STEMI Equivalent?

The Evolution of LBBB as STEMI Equivalent

Why the Change in 2013?

Per Rosen's Emergency Medicine: "A new or presumably new LBBB is no longer considered a STEMI equivalent pattern."

So What Makes It a STEMI Equivalent NOW?

The Crucial Distinction

New LBBB alone        → NOT a STEMI equivalent (2013 onwards)
New LBBB + Sgarbossa+ → STEMI EQUIVALENT → Reperfusion NOW
New LBBB + symptoms but Sgarbossa negative → Urgent cardiology consult, 
                         serial ECGs, troponin - NOT automatic cath lab activation

This Patient's ECG - Final Verdict

1. New LBBB (QRS 174ms, classic morphology)
2. Sgarbossa Criterion 1 positive - concordant ST elevation ≥1mm in V4-V5 (most specific sign, score 5/10, threshold is 3)
3. Modified Sgarbossa (Smith) positive - ST/S ratio ≥0.25 in V2 and V3
4. Active chest pain