Management of Sinus Rhythm with Short PR Interval in Pregnancy
A pregnant patient with sinus rhythm and an isolated short PR interval (<120 ms) without a widened QRS or delta wave requires no further cardiac evaluation or intervention, as this finding is benign and does not represent Wolff-Parkinson-White syndrome or any pathologic condition. 1
Key Diagnostic Distinction
The critical determination is whether true ventricular pre-excitation (WPW pattern) is present:
- Isolated short PR interval alone: PR <120 ms with normal QRS duration and no delta wave - this is benign and requires no workup 1
- WPW pattern: PR <120 ms PLUS delta wave (slurring of initial QRS) PLUS QRS duration >120 ms - this requires evaluation 1
When No Further Evaluation is Needed
If the 12-lead ECG shows only a short PR interval with normal QRS morphology and duration, no echocardiogram, stress testing, or electrophysiology consultation is indicated. 1 This applies to asymptomatic pregnant patients, as the short PR interval in isolation does not predispose to arrhythmias or sudden death 1.
When Evaluation IS Required
If the ECG demonstrates the complete WPW pattern (short PR + delta wave + wide QRS), then risk stratification becomes necessary even in pregnancy:
- Exercise stress test to assess for abrupt loss of pre-excitation at higher heart rates, suggesting a low-risk accessory pathway 1
- Echocardiography to evaluate for Ebstein's anomaly and cardiomyopathy, which are associated with WPW 1
- Electrophysiology study if non-invasive testing cannot confirm a low-risk pathway, to determine the shortest pre-excited RR interval during atrial fibrillation 1
Common Pitfall to Avoid
Do not confuse an isolated short PR interval with WPW syndrome. The absence of a delta wave and normal QRS duration definitively excludes ventricular pre-excitation 1. Unnecessary cardiac workup in pregnancy exposes the patient to radiation (if stress imaging is performed) and creates unwarranted anxiety when the finding is entirely benign.
Pregnancy-Specific Considerations
Pregnancy itself can precipitate arrhythmias through hormonal effects, autonomic tone changes, and hemodynamic perturbations 2. However, an isolated short PR interval does not increase arrhythmia risk during pregnancy, labor, or delivery 1. Normal obstetric management is appropriate with no cardiac restrictions 1.