What is the first step in evaluating a pediatric patient who lost consciousness while playing and has an ejection systolic murmur on auscultation?

Immediate Diagnostic Approach: ECG First

In a pediatric patient who lost consciousness during exertion and has an ejection systolic murmur on examination, obtain a 12-lead ECG immediately as the first diagnostic step. This presentation represents exertional syncope with a cardiac murmur—a high-risk combination that demands urgent evaluation for potentially life-threatening cardiac conditions before proceeding to echocardiography 1.

Why ECG Takes Priority Over Echocardiography

Critical Risk Stratification

• Exertional syncope is a red flag for sudden cardiac death risk and specifically raises suspicion for hypertrophic cardiomyopathy (HCM), long QT syndrome (LQTS), and catecholaminergic polymorphic ventricular tachycardia (CPVT) 1
• The ACC/AHA/HRS guidelines explicitly state that exertional syncope, especially mid-exertional syncope, should result in a high index of suspicion for a cardiac etiology 1
• A 12-lead ECG should be performed in ALL pediatric patients presenting with syncope as part of the mandatory initial evaluation 1

ECG Provides Immediate Life-Saving Information

The ECG can immediately identify:

• Channelopathies (LQTS, Brugada syndrome) that are major causes of cardiac-related syncope and sudden death in young people 1
• Pre-excitation patterns (Wolff-Parkinson-White syndrome) that require immediate electrophysiology referral due to sudden death risk 1
• Hypertrophic cardiomyopathy patterns (left ventricular hypertrophy, deep Q waves, T-wave inversions) 1
• Arrhythmias or conduction abnormalities that may have caused the syncopal episode 1

Guideline-Mandated Sequence

The 2017 ACC/AHA/HRS Syncope Guidelines give a Class I recommendation (highest level) that evaluation including a 12-lead ECG should be performed in all pediatric patients presenting with syncope 1. This ECG is part of the initial risk stratification that determines whether the patient needs urgent intervention, admission, or can proceed to outpatient echocardiography 1.

The Role of Echocardiography (Second Step)

When to Proceed to Echo

Echocardiography is essential but follows the ECG in the diagnostic algorithm 1:

• Echo should be performed when there is suspected congenital heart disease, cardiomyopathy, or primary rhythm disorder based on history, examination, or ECG findings 1
• The ejection systolic murmur in this patient makes structural heart disease (particularly HCM or aortic stenosis causing left ventricular outflow obstruction) highly likely 1
• Noninvasive diagnostic testing (including echocardiography) receives a Class I recommendation for pediatric patients with syncope and suspected structural heart disease 1

Why Not Echo First?

• Time-sensitive arrhythmias require immediate ECG documentation before they resolve spontaneously 1
• An abnormal ECG may change the urgency of management (immediate admission vs. outpatient workup) before echo is even obtained 1
• ECG is faster, universally available, and provides critical information that guides the interpretation of subsequent echo findings 1

Critical Clinical Context

High-Risk Features Present in This Case

This patient has multiple red flags for cardiac syncope 1:

1. Exertional syncope (occurred "while playing")
2. Ejection systolic murmur (suggests structural abnormality)
3. Loss of consciousness (not just presyncope)

Common Pitfall to Avoid

Do not assume this is benign vasovagal syncope despite the fact that neurally mediated syncope accounts for 75% of pediatric syncope 1. The combination of exertional syncope and a cardiac murmur places this patient in the 1.5-6% of pediatric syncope cases that are cardiac in origin—and these carry risk of sudden cardiac death 1.

Algorithmic Approach

Step 1: Obtain 12-lead ECG immediately 1

• If ECG shows LQTS, Brugada, pre-excitation, or significant arrhythmia → immediate cardiology/EP referral 1
• If ECG shows HCM pattern → proceed urgently to echo and cardiology referral 1
• If ECG is normal → still proceed to echo given the murmur and exertional syncope 1

Step 2: Obtain echocardiography 1

• Evaluate for HCM, aortic stenosis, anomalous coronary arteries, or other structural abnormalities
• Even with normal ECG, structural disease can be present 1

Step 3: Consider exercise stress testing 1

• Particularly useful if LQTS or CPVT suspected (adrenergically mediated arrhythmias) 1
• Should be performed in controlled environment with advanced life support available 1

Step 4: Extended cardiac monitoring if indicated 1

• Event recorder or implantable loop recorder if arrhythmia suspected but not captured 1
• Diagnostic yield of prolonged monitoring in pediatric syncope is approximately 43% 1

Bottom Line

The answer is A (ECG), not B (Echo), because the ECG must be obtained first to identify immediately life-threatening conditions and guide the urgency and interpretation of subsequent testing including echocardiography 1. Both tests are ultimately necessary in this high-risk patient, but the sequence matters for patient safety and appropriate risk stratification.