What is the best course of action for a 47-year-old asymptomatic female patient in sinus rhythm with a short PR (P-R) interval?

Management of Asymptomatic 47-Year-Old Female with Short PR Interval

For an asymptomatic 47-year-old female with a short PR interval in sinus rhythm, the critical first step is obtaining a 12-lead ECG to assess for the presence of a delta wave and QRS widening to differentiate between Wolff-Parkinson-White (WPW) pattern and an isolated short PR interval, as this distinction completely determines management. 1

Initial ECG Assessment

The immediate priority is distinguishing WPW pattern from isolated short PR interval:

• WPW pattern is defined by short PR interval (<120 ms), delta wave (slurred initial QRS upstroke), and wide QRS (>120 ms), representing ventricular pre-excitation via an accessory pathway bypassing the AV node 1
• Isolated short PR shows a short PR interval (<120 ms) without delta wave or QRS widening 1, 2

This differentiation is critical because WPW pattern carries a sudden cardiac death risk of 0.15-0.39% over 3-10 years, and cardiac arrest can be the first manifestation in approximately 50% of affected patients 1

Management Algorithm Based on ECG Findings

If WPW Pattern is Present (Delta Wave + Wide QRS)

Even in asymptomatic patients, WPW pattern requires comprehensive evaluation because sudden death can occur without warning: 1

• Obtain detailed symptom history specifically for palpitations, syncope, or pre-syncope 1
• Perform echocardiography to assess for structural abnormalities, particularly Ebstein's anomaly and hypertrophic cardiomyopathy 1
• Conduct exercise stress testing to assess for intermittent pre-excitation 1
• Consider electrophysiology study for definitive risk stratification (Class IIa recommendation) 1
• Catheter ablation is the definitive treatment given the sudden death risk, even in asymptomatic patients 1

If Isolated Short PR Interval (No Delta Wave, Normal QRS)

Asymptomatic patients with isolated short PR and no structural heart disease generally do not require further evaluation or treatment: 1

However, specific conditions must be excluded:

Metabolic/Storage Diseases to Consider:

• Fabry disease: X-linked lysosomal storage disorder presenting with short PR, sinus bradycardia, and left ventricular hypertrophy; consider especially if LVH is present or multisystem symptoms exist 1
• Pompe disease: Rare genetic disorder with short PR, extremely tall QRS complexes, and cardiomegaly 1

Physiologic Causes:

• Enhanced sympathetic tone or vagal withdrawal (normal in young healthy individuals during exercise) 1
• Pheochromocytoma: Excess catecholamines can cause accelerated AV nodal conduction with short PR interval 3

Specific Diagnostic Steps for Isolated Short PR

1. Measure the exact PR interval from the beginning of the P wave to the beginning of the QRS complex; short PR is defined as <120 ms 1, 2

2. Verify proper ECG calibration, particularly if QRS voltage appears unusually high (consider Pompe disease) 1

3. Obtain echocardiography if any suggestion of left ventricular hypertrophy to exclude Fabry disease before attributing findings to other causes 1

4. Check thyroid function to exclude hyperthyroidism as a cause of enhanced AV nodal conduction 4

5. Review medications and substances including beta-agonists, caffeine, and stimulants 4

Common Pitfalls to Avoid

• Never dismiss WPW pattern as benign, even in completely asymptomatic patients, as sudden death can occur without warning 1
• The presence or absence of a delta wave completely changes management; careful ECG review is essential 1
• Do not attribute short PR with LVH to hypertension or athletic heart without considering Fabry disease 1
• Use age-appropriate PR interval norms, particularly important in younger patients 1

Follow-Up Recommendations

For isolated short PR in an asymptomatic patient with normal echocardiogram and no metabolic abnormalities:

• No specific restrictions on physical activity 1
• No routine follow-up required unless symptoms develop 1
• Patient education about seeking evaluation if palpitations, syncope, or pre-syncope occur 1