From the Guidelines
A PR interval of 218 milliseconds is considered abnormal and represents first-degree atrioventricular (AV) block. The normal PR interval range is typically between 120-200 milliseconds, so a measurement of 218 ms exceeds this upper limit, as defined by the 2019 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1. First-degree AV block indicates delayed conduction of electrical impulses from the atria to the ventricles through the AV node. While first-degree AV block is often asymptomatic and may not require specific treatment in otherwise healthy individuals, it should be evaluated by a healthcare provider, especially if the patient has symptoms like dizziness, fatigue, or syncope. This finding may be caused by various factors including aging, medications (particularly beta-blockers, calcium channel blockers, or digoxin), electrolyte abnormalities, increased vagal tone, or underlying heart disease. According to the guideline, first-degree atrioventricular block is defined as P waves associated with 1:1 atrioventricular conduction and a PR interval >200 ms 1. In some cases, it may be a normal variant, but it could also represent early evidence of conduction system disease that might progress to more advanced heart block. Regular cardiac follow-up is typically recommended to monitor for any progression. Key points to consider include:
- The definition of first-degree AV block and its implications for patient care
- The potential causes of first-degree AV block, including medications and underlying heart disease
- The importance of regular cardiac follow-up to monitor for progression of the condition.
From the Research
PR Interval of 218 Milliseconds
- A PR interval of 218 milliseconds is considered prolonged, as the normal PR interval is typically less than 200 ms 2.
- First-degree atrioventricular block is defined as a PR interval longer than 200 ms, and a PR interval of 218 ms falls into this category 2.
- While first-degree atrioventricular block was previously considered benign, recent studies suggest that it may not be entirely harmless, especially in patients with symptoms or underlying heart disease 3, 4.
Clinical Significance
- A PR interval of 218 ms may be associated with symptoms such as exercise intolerance, palpitations, and fainting spells, especially if it is extremely prolonged 5.
- First-degree atrioventricular block has been linked to an increased risk of heart failure and death in patients with stable coronary artery disease, even after adjusting for other factors 4.
- However, the clinical significance of a PR interval of 218 ms specifically is not well-established, and more research is needed to determine its potential impact on health outcomes.
Comparison to Other Studies
- A study published in 2011 found that first-degree atrioventricular block was associated with heart failure and death in patients with stable coronary artery disease, with a PR interval of 220 ms or greater considered abnormal 4.
- Another study published in 2014 reported a case of a patient with a PR interval of 560 ms, which is significantly longer than 218 ms, and was associated with atrioventricular dissociation and pseudo-pacemaker syndrome 5.
- Overall, while a PR interval of 218 ms may not be considered extremely prolonged, it is still longer than normal and may be associated with some clinical significance, especially in certain patient populations 3, 6.