What is the treatment for a short PR interval on an electrocardiogram (ECG) in a pediatric patient?

Management of Short PR Interval in Pediatric ECG

For pediatric patients with a short PR interval on ECG, evaluation for Wolff-Parkinson-White (WPW) syndrome is essential, as this condition requires risk stratification and possible electrophysiology study to determine the need for catheter ablation.

Initial Assessment

When a short PR interval is identified on a pediatric ECG, the following evaluation should be performed:

1. Complete ECG analysis - Look for:

   • PR interval <0.12 seconds
   • Delta wave (slurring of initial QRS segment)
   • QRS complex widening >0.12 seconds
   • Secondary repolarization changes (ST-T wave changes discordant to delta wave) 1

2. Symptom assessment:

   • History of palpitations
   • Syncope or presyncope
   • Chest pain during exertion
   • Family history of sudden cardiac death

Risk Stratification

The presence of a short PR interval may indicate WPW syndrome, which carries a risk of sudden cardiac death even in asymptomatic patients:

• Studies show that symptomatic and asymptomatic children with ventricular pre-excitation have similar potential risk for sudden cardiac death 2
• Cardiac arrest may be the first manifestation in 80% of children with a life-threatening accessory pathway 3

Management Algorithm

For Symptomatic Patients (WPW Syndrome)

1. Immediate referral to pediatric cardiologist/electrophysiologist

2. Electrophysiology study (EPS) is indicated, particularly if:

   • Patient has experienced syncope
   • Patient has documented tachyarrhythmias 4
   • Refractory period of accessory pathway needs assessment

3. Catheter ablation is recommended if:

   • Patient is symptomatic
   • Accessory pathway refractory period is ≤240 ms 4

For Asymptomatic Patients (WPW Pattern)

1. Risk assessment with:

   • Exercise stress test
   • 24-hour ambulatory ECG monitoring
   • Echocardiogram to rule out structural heart disease 4

2. Consider EPS if:

   • Intermittent pre-excitation is noted (does not guarantee lower risk) 5
   • Patient participates in competitive sports
   • High-risk occupation or activities

3. Catheter ablation may be considered even in asymptomatic patients with high-risk features on EPS

Medication Management

• Avoid digoxin or verapamil in infants with ventricular tachycardia that has not been excluded 4
• For patients with confirmed WPW and paroxysmal supraventricular tachycardia:
  • Flecainide may be considered (starting dose 50 mg/m² body surface area daily for children under 6 months, up to 100 mg/m² for older children) 6
  • Careful monitoring required with frequent ECGs and plasma level checks

Important Caveats

1. Do not assume intermittent pre-excitation is low risk - Research shows that intermittent WPW in children does not necessarily indicate lower risk of sudden death 5

2. Avoid certain medications in undiagnosed short PR interval:

   • Digoxin and calcium channel blockers can accelerate conduction through accessory pathways and precipitate ventricular fibrillation in WPW patients with atrial fibrillation 7

3. Consider other causes of short PR interval:

   • Lown-Ganong-Levine syndrome
   • Glycogen storage diseases
   • Hypercalcemia (can shorten PR interval)

4. Recognize that pediatric patients with WPW may be at higher risk than adults due to:

   • Potential for faster conduction through accessory pathways
   • Difficulty in recognizing and reporting symptoms
   • Longer life exposure to risk

The management of short PR interval in pediatric patients requires careful evaluation and risk stratification, with a low threshold for referral to pediatric electrophysiology specialists, particularly when associated with symptoms or high-risk features.