Evaluation and Management of Short PR Interval

Definition and Recognition

A short PR interval is defined as <120 ms on the surface ECG, according to the American College of Cardiology, and requires consideration of the presence or absence of a delta wave and QRS widening to distinguish between isolated short PR and Wolff-Parkinson-White (WPW) pattern 1, 2
The critical distinction between isolated short PR and WPW pattern is the presence of a delta wave and QRS widening >120 ms, which defines the WPW pattern and necessitates comprehensive risk stratification due to the risk of sudden cardiac death, as recommended by the American College of Cardiology 1, 2
Short PR with delta wave occurs due to an accessory pathway bypassing the AV node, allowing early ventricular activation, and is a key characteristic of WPW pattern 2

In asymptomatic athletes or patients with isolated short PR interval without delta wave or QRS widening, no further cardiac evaluation is indicated, as stated by the American College of Cardiology, and this represents either a normal variant or Lown-Ganong-Levine syndrome, neither requiring intervention in asymptomatic individuals 1, 2
Age-appropriate norms should be used when interpreting PR intervals, particularly adjusting for gestational age in infants, to ensure accurate diagnosis and management, as recommended by the American Academy of Pediatrics and the American College of Cardiology 3

All patients with WPW pattern require comprehensive evaluation regardless of symptoms, as sudden cardiac death can be the first manifestation in approximately 50% of cases, and the American College of Cardiology recommends rigorous evaluation and management for these patients 2
The evaluation should include a detailed symptom history, 12-lead ECG, and echocardiography to evaluate for Ebstein's anomaly and structural cardiomyopathy, both associated with WPW, as recommended by the American College of Cardiology 1, 2

A detailed symptom history, including palpitations, presyncope, syncope, or family history of sudden death, should be obtained, as recommended by the American College of Cardiology, to assess the risk of sudden cardiac death 2
A 12-lead ECG should be performed to document PR interval, delta wave morphology, and QRS duration, and to evaluate for signs of pre-excitation, as recommended by the American College of Cardiology 1
Echocardiography should be performed to evaluate for Ebstein's anomaly and structural cardiomyopathy, both associated with WPW, as recommended by the American College of Cardiology 1, 2

Exercise stress testing is the first-line non-invasive test to assess accessory pathway risk, as recommended by the American College of Cardiology, and should be performed to evaluate for signs of pre-excitation and to assess the risk of sudden cardiac death 1, 2
Low-risk features on exercise testing include abrupt, complete loss of pre-excitation at higher heart rates and intermittent pre-excitation during sinus rhythm on resting ECG, as defined by the American College of Cardiology, and patients with these features may be considered low-risk for sudden cardiac death 1, 2

Electrophysiological study (EPS) should be performed when non-invasive testing cannot confirm a low-risk pathway or is inconclusive, as recommended by the American College of Cardiology, or when the patient is a competitive athlete involved in moderate or high-intensity sports 1, 2
High-risk criteria at EPS requiring ablation include shortest pre-excited RR interval during induced atrial fibrillation ≤250 ms, multiple accessory pathways, and history of symptomatic tachycardia, as defined by the American College of Cardiology, and patients with these criteria should undergo ablation to reduce the risk of sudden cardiac death 1, 2

Transcatheter ablation is recommended for patients with shortest pre-excited RR interval ≤250 ms during atrial fibrillation at EPS, symptomatic patients with documented tachycardia, and competitive athletes with high-risk features who wish to continue sports participation, as recommended by the American College of Cardiology 1, 2

Observation without ablation is appropriate for asymptomatic patients with clearly documented low-risk pathway features, such as intermittent pre-excitation or abrupt loss at high heart rates, as recommended by the American College of Cardiology, and patients who decline ablation after informed discussion of sudden death risk 1, 2

Short PR interval is present in 75% of infantile Pompe disease cases and appears on ECG alongside very tall QRS complexes, as reported in the medical literature, and when evaluating infants with cardiomegaly, short PR interval should prompt consideration of Pompe disease and measurement of serum creatine kinase 3
Caution is needed with voltage calibration, as extremely high QRS voltage may lead operators to decrease gain, missing this diagnostic clue, and age-appropriate PR interval norms should be used when interpreting PR intervals in infants, as recommended by the American Academy of Pediatrics 3

Short PR interval without delta wave in athletes is a normal variant requiring no evaluation, as stated by the American College of Cardiology, and athletes with WPW pattern require the same rigorous evaluation as non-athletes, with particular attention to sports participation decisions 1, 2

Never dismiss WPW pattern as benign, even in asymptomatic patients, as sudden death can occur without warning, and do not confuse isolated short PR with WPW pattern, as the presence or absence of delta wave and QRS widening completely changes management, as recommended by the American College of Cardiology 1, 2
Ensure proper ECG calibration when evaluating for short PR, particularly in conditions like Pompe disease where QRS voltage may be extremely high, and use age-appropriate PR interval norms, especially in pediatric populations, as recommended by the American Academy of Pediatrics and the American College of Cardiology 3