From the Guidelines
A patient with a prolonged PR interval on an electrocardiogram (EKG) should generally see a cardiologist for evaluation, especially if the PR interval exceeds 200 milliseconds. This finding, known as first-degree atrioventricular (AV) block, indicates delayed electrical conduction between the atria and ventricles. While first-degree AV block is often benign and may not require treatment, it can sometimes signal underlying heart conditions such as coronary artery disease, cardiomyopathy, or effects of certain medications like beta-blockers, calcium channel blockers, or digoxin 1. The cardiologist will assess whether the prolonged PR interval is an isolated finding or part of a more serious conduction disorder. They may recommend additional testing such as a 24-hour Holter monitor, exercise stress test, or echocardiogram to evaluate heart function. Patients should bring a list of all current medications to the appointment, as some drugs can affect cardiac conduction. If the prolonged PR interval is medication-related, the cardiologist might adjust dosages or recommend alternative treatments. While waiting for the cardiology appointment, patients should report any symptoms like dizziness, fainting, chest pain, or shortness of breath to their healthcare provider immediately, as these could indicate progression to a more serious heart block. According to the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay, patients with first-degree AV block may experience symptoms of fatigue or exertional intolerance if the PR interval is long enough to allow for loss of atrioventricular synchrony 1. Therefore, it is essential for patients with a prolonged PR interval to consult a cardiologist for proper evaluation and management to prevent potential complications and improve quality of life. Key considerations for the cardiologist's evaluation include:
- Assessing the degree of AV block and its potential impact on cardiac function
- Evaluating for underlying heart conditions that may be contributing to the prolonged PR interval
- Considering the patient's symptoms and medical history to determine the best course of treatment
- Discussing the potential risks and benefits of pacing or other treatments with the patient 1.
From the Research
Prolonged PR Interval on EKG
A prolonged PR interval on an electrocardiogram (EKG) is a condition where the time between the onset of the P wave and the start of the QRS complex is longer than normal. This condition is also known as first-degree atrioventricular (AV) block.
Clinical Significance
The clinical significance of a prolonged PR interval is a topic of ongoing research. Some studies suggest that it may be associated with increased mortality and morbidity, while others have found no significant association.
- A study published in the European Heart Journal in 2014 found that prolonged PR interval was not associated with an increased risk of all-cause or cardiovascular mortality in a middle-aged population 2.
- However, a systematic review and meta-analysis published in Heart in 2016 found that prolonged PR interval was associated with an increased risk of mortality, heart failure, and atrial fibrillation 3.
- Another study published in the Journal of Cardiovascular Electrophysiology in 2017 found that patients with advanced systolic heart failure and prolonged PR intervals may benefit from cardiac resynchronization therapy with defibrillation (CRT-D) 4.
Management
The management of a patient with a prolonged PR interval on EKG depends on the underlying cause and the presence of symptoms.
- Asymptomatic patients with bifascicular block and a prolonged PR interval may not require prophylactic pacing, according to a study published in Thorax in 1981 5.
- However, patients with symptoms such as syncope or myocardial infarction may require further evaluation and treatment.
- The American Heart Association recommends that patients with first-degree AV block be evaluated for underlying cardiac disease and monitored for the development of higher-degree AV block 6.
Referral to Cardiology
Whether a patient with a prolonged PR interval on EKG should see a cardiologist depends on the individual case.
- Patients with symptoms such as chest pain, shortness of breath, or syncope should be referred to a cardiologist for further evaluation.
- Asymptomatic patients with a prolonged PR interval may not require referral to a cardiologist, but should be monitored for the development of symptoms or changes in their EKG.
- A study published in Heart Rhythm in 2010 found that measurement of the PR interval during recovery from physical exertion may improve cardiovascular mortality risk stratification 6.