ECG Analysis - 12-Year-Old Male with Chest Pain Radiating to Left Arm

ECG Technical Details

• Settings: AUTO 10 mm/mV, 25 mm/s, 150 Hz filter
• Two ECGs provided (the second is dated 2026-05-26, 08:16)
• Leads: Full 12-lead

ECG Findings (Both Tracings)

Key Differential Diagnosis for This Presentation

1. ALCAPA (Anomalous Left Coronary Artery from the Pulmonary Artery) - TOP CONCERN

• ECG shows ischemic changes (ST elevation, Q waves in lateral leads) in a child
• Per Rosen's Emergency Medicine: "A rare but potentially fatal congenital cardiac abnormality detected by ECG, anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA), will show ischemic changes. Older children and adolescents may have acute-on-chronic ischemic symptoms."
• The LCA drains retrograde into the pulmonary artery, causing chronic LV ischemia
• Presentation: chest pain, dyspnea on exertion, syncope

2. Myocarditis

• ST elevation (often diffuse but can be regional) in a child
• Frequently follows a viral illness (check for recent fever, URI, GI illness)
• Elevated troponin would support this
• ST changes in multiple leads without clear "culprit vessel" territory

3. Hypertrophic Cardiomyopathy (HCM)

• Chest pain + left arm radiation on exertion in a child
• LV hypertrophy changes on ECG
• ST changes from subendocardial ischemia
• Check for family history of sudden death

4. Acute Pericarditis

• Diffuse ST elevation with saddle-shaped morphology
• PR depression (look carefully in II and V5)
• Usually positional pain, but can radiate

5. Coronary Artery Anomaly (Other - e.g., anomalous origin from wrong sinus)

• Sudden exertional chest pain in young athletes
• Exercise-triggered ischemia

6. Kawasaki Disease Sequelae

• Coronary aneurysm with thrombosis or stenosis
• Prior history of prolonged fever/rash in early childhood

7. Drug-related / Toxicology

• Cocaine, stimulants, synthetic cannabinoids can cause coronary spasm and MI even in adolescents

Immediate Management Protocol

1. Troponin I/T + serial troponin at 3-6 hours - myocardial injury marker
2. CK-MB - additional myocardial damage marker
3. BNP/NT-proBNP - ventricular stress marker
4. CBC, CRP, ESR - inflammation (myocarditis, pericarditis)
5. 2D Echocardiogram with Doppler - MOST IMPORTANT NEXT STEP - assess:
   • LV systolic function (global and regional wall motion abnormalities)
   • Coronary artery origins (ALCAPA)
   • Pericardial effusion
   • Septal thickness (HCM)
   • Mitral regurgitation (ALCAPA marker)
6. Chest X-ray - cardiomegaly, pulmonary edema
7. Electrolytes, renal function, magnesium
8. Drug screen if relevant history

• Continuous cardiac monitoring (telemetry)
• IV access
• O2 saturation monitoring
• Keep NPO until echo result available

• Urgent pediatric cardiology consultation
• If troponin elevated or echo shows wall motion abnormality: consider transfer to tertiary pediatric cardiac center

What the ECG Specifically Suggests

• Anterolateral ischemia - territory of the LAD/LCx
• In pediatric context: ALCAPA causes exactly this - chronic anterolateral LV ischemia
• Myocarditis is also very possible given the diffuse nature

Red Flags Demanding Immediate Action

• Age 12 + chest pain radiating to left arm = never dismiss without cardiac workup
• ST changes on ECG in a child = cardiac emergency until proven otherwise
• Sinus tachycardia at rest may indicate pain, anxiety, or compensated low cardiac output

Bottom line: Admit this child, get urgent echo and troponin, involve pediatric cardiology immediately. ALCAPA and myocarditis are the leading diagnoses and both require urgent intervention. Do not discharge without a definitive explanation for the ECG changes.

• Rosen's Emergency Medicine, 9th ed. (Pediatric ECG and ALCAPA section)
• Braunwald's Heart Disease (ALCAPA - Anomalous Coronary Artery from Pulmonary Artery, p. 3467-3477)

Ruling Out Myocarditis - Systematic Approach

Step 1 - Clinical History (Features that SUPPORT myocarditis)

• Preceding viral illness - fever >38°C in the last 30 days, malaise, chills
• Respiratory symptoms - recent cough, sore throat, URI in past 2-4 weeks
• GI symptoms - vomiting, diarrhea (enteric viral prodrome)
• Autoimmune history - SLE, JIA, inflammatory bowel disease
• Drug/toxin exposure - medications, supplements, substance use
• Prior episode of similar chest pain

Step 2 - ECG Clues to Distinguish Myocarditis vs. Ischemia

Step 3 - Laboratory Investigations

Step 4 - Echocardiography (MOST ACCESSIBLE - Do First)

Step 5 - Cardiac MRI (CMR) - GOLD STANDARD NON-INVASIVE TEST

• Myocarditis: Mid-wall or epicardial LGE, non-coronary territory
• Ischemia/ALCAPA: Subendocardial or transmural LGE in a coronary artery distribution
• HCM: LGE at RV insertion points or within hypertrophied segments

Step 6 - Coronary Angiography / CT Coronary Angiography

• CT coronary angiography can confirm or exclude ALCAPA/coronary anomalies non-invasively
• Normal coronary anatomy on imaging shifts the diagnosis strongly toward myocarditis
• If echo shows coronary origins clearly from the aorta = ALCAPA excluded

Step 7 - Endomyocardial Biopsy (EMB) - The True Gold Standard

• Diagnosis remains unclear after echo + CMR
• Suspected fulminant myocarditis needing specific treatment
• Suspected giant cell myocarditis (GCM), cardiac sarcoidosis, or necrotizing eosinophilic myocarditis - these have specific treatments and require tissue diagnosis
• Hemodynamic compromise requiring circulatory support

Summary: Step-by-Step Ruling Out Algorithm for This Child

1. History → viral prodrome? autoimmune? drugs?
         ↓
2. ECG → ST shape? PR depression? Non-coronary distribution?
         ↓
3. Labs → Troponin (serial), CRP/ESR, CBC differential, viral serology
         ↓
4. Echo → LV function, wall motion, coronary origins, pericardial effusion
         ↓
5. CMR → T2/T1 mapping + LGE pattern (mid-wall = myocarditis; subendocardial = ischemia)
         ↓
6. If coronary disease not excluded → CTA coronaries or angiography (rule out ALCAPA)
         ↓
7. If diagnosis still uncertain + fulminant/specific type suspected → EMB

• CMR shows no myocardial edema (T2), no elevated T1/ECV, and no LGE
• Echo shows normal LV function, no pericardial effusion, no RWMA
• Troponin normal or rapidly normalizing
• Inflammatory markers (CRP, ESR) are normal
• Viral serology negative

• Fuster and Hurst's The Heart, 15th ed. (Table 20-4, Diagnostic Approach to Myocarditis)
• Harrison's Principles of Internal Medicine, 22nd ed. (Myocarditis, CMR LGE pattern)
• Hutchinson Z & Law Y. Myocarditis in children: diagnosis and management. JHLT Open. 2025 [PMID 40837541]
• Goldberg JF et al. Myocarditis in children 2024. Curr Opin Cardiol. 2024 [PMID 38661130]