Can WPW Cause Bradycardia?
No, Wolff-Parkinson-White (WPW) syndrome does not cause bradycardia—it is fundamentally a disorder of tachyarrhythmias caused by an accessory pathway that bypasses the AV node, predisposing patients to rapid heart rates, not slow ones. 1, 2
Why WPW Is Not Associated with Bradycardia
WPW syndrome is defined by the presence of an accessory electrical pathway that conducts impulses more rapidly than the normal AV node, creating ventricular pre-excitation and predisposing to supraventricular tachyarrhythmias, not bradycardia. 1, 2, 3
The characteristic arrhythmias in WPW are all tachycardias, including orthodromic AVRT (90-95% of episodes), antidromic AVRT (5-10%), atrial fibrillation with rapid ventricular response (up to 50% of patients), and potentially life-threatening ventricular fibrillation. 1, 2, 4
The accessory pathway provides an additional route for electrical conduction, which inherently increases—not decreases—the potential for rapid heart rates by bypassing the rate-limiting function of the AV node. 3, 5
The Actual Clinical Concern: Tachyarrhythmias
The primary risk in WPW is sudden cardiac death from rapid ventricular rates, with an incidence of 0.15-0.39% over 3-10 years, occurring when atrial fibrillation conducts rapidly over the accessory pathway (shortest pre-excited R-R interval <250 ms) and degenerates into ventricular fibrillation. 6, 1, 7
Symptomatic patients experience palpitations, syncope, dizziness, chest pain, and shortness of breath during tachyarrhythmia episodes, not symptoms of bradycardia such as persistent fatigue or exercise intolerance from slow heart rates. 1
Important Caveat: Post-Ablation Bradycardia Risk
The only scenario where bradycardia might occur in a WPW patient is as a complication of catheter ablation, with major complications including complete heart block, right bundle-branch block, or left bundle-branch block occurring in 0.1-0.9% of cases. 1
This iatrogenic bradycardia results from inadvertent damage to the normal conduction system during ablation, not from the WPW syndrome itself. 1
Distinguishing WPW from Bradyarrhythmias
Bradyarrhythmias (sinus node dysfunction and AV conduction disturbances) are entirely separate entities that account for approximately 20% of documented sudden cardiac death but are not caused by or associated with accessory pathways. 6
If a patient with apparent WPW pattern presents with bradycardia, consider alternative diagnoses such as coexisting sinus node dysfunction, medication effects (particularly if AV nodal blockers were inappropriately given), or misdiagnosis of the ECG pattern. 6