What is the best course of action for a 27-year-old female (YOF) presenting to the emergency department (ED) with palpitations and an electrocardiogram (ECG) showing sinus rhythm with first-degree atrioventricular (AV) block and a heart rate (HR) of 68?

Management of First-Degree AV Block in a Young Female with Palpitations

First-degree AV block with palpitations in a 27-year-old female with normal heart rate does not require pacemaker implantation or specific treatment, but warrants further evaluation to identify potential underlying causes. 1

Initial Assessment

When evaluating this patient, focus on:

• Correlation between palpitation symptoms and ECG findings
• Presence of additional symptoms (dizziness, syncope, pre-syncope)
• Hemodynamic stability (normal HR of 68 suggests stability)
• PR interval duration (specific measurement should be documented)

Diagnostic Approach

The first-degree AV block in this young patient requires investigation:

1. Complete history:

   • Timing, duration, and triggers of palpitations
   • Associated symptoms (dizziness, chest pain, shortness of breath)
   • Medication use (including OTC and recreational substances)
   • Family history of cardiac disease or sudden death

2. Laboratory studies:

   • Electrolytes (particularly potassium, magnesium, calcium)
   • Thyroid function tests
   • Complete blood count
   • Drug screen if clinically indicated

3. Additional cardiac evaluation:

   • 12-lead ECG (to assess PR interval duration and other abnormalities)
   • Ambulatory ECG monitoring (event monitor for 2 weeks if symptoms are intermittent) 2, 3
   • Echocardiogram to evaluate for structural heart disease

Management Considerations

Immediate Management

• Reassurance that isolated first-degree AV block with normal heart rate is generally benign 1
• No immediate intervention is required in the ED for a hemodynamically stable patient
• Observation if the patient is symptomatic during the visit

Long-term Management

• According to guidelines, permanent pacemaker implantation is NOT indicated for asymptomatic first-degree AV block 1
• Pacemaker implantation is only reasonable if:
  • PR interval is markedly prolonged (>300 ms) AND
  • Patient has symptoms similar to pacemaker syndrome 1, 4

Important Considerations

Potential Causes to Investigate

• Increased vagal tone
• Medication effects (beta-blockers, calcium channel blockers)
• Electrolyte abnormalities
• Inflammatory conditions (myocarditis)
• Early manifestation of conduction system disease
• Infiltrative diseases (less common in young patients)

Follow-up Recommendations

• Cardiology referral for further evaluation
• Consider extended monitoring with insertable cardiac monitor if symptoms persist but initial workup is negative 5
• Periodic ECG monitoring to assess for progression of conduction disease

Pitfalls to Avoid

1. Dismissing palpitations as anxiety without adequate investigation
2. Failing to recognize that first-degree AV block may be the first sign of progressive conduction disease in some patients 5
3. Missing potentially reversible causes (medications, electrolyte abnormalities)
4. Unnecessary pacemaker implantation for isolated first-degree AV block without symptoms of hemodynamic compromise 1

Remember that while guidelines clearly state that isolated first-degree AV block with normal heart rate does not require pacemaker implantation, it should prompt appropriate investigation to identify any underlying cardiac pathology, especially in a young patient presenting with palpitations.