From the Guidelines
Electrocardiogram (EKG) changes in Wolff-Parkinson-White (WPW) syndrome are characterized by a short PR interval, a widened QRS complex, and a delta wave, which is a result of ventricular pre-excitation due to an accessory electrical pathway. These changes are critical for diagnosis and management, as they can lead to life-threatening arrhythmias 1. The presence of a delta wave, which appears as a slurred upstroke at the beginning of the QRS complex, is a hallmark of WPW syndrome and indicates early activation of the ventricles through the accessory pathway.
Key EKG Findings
- Short PR interval (less than 120 milliseconds)
- Widened QRS complex (greater than 120 milliseconds)
- Delta wave, representing early activation of the ventricles through the accessory pathway These findings are a result of the accessory pathway, also known as the Bundle of Kent, which allows electrical impulses to bypass the normal atrioventricular (AV) node delay, creating ventricular pre-excitation 1.
Clinical Implications
The EKG changes in WPW syndrome can lead to potentially life-threatening arrhythmias, such as atrial fibrillation (AF) with rapid ventricular response, which can increase the risk of sudden cardiac death (SCD) 1. Therefore, recognition of these EKG changes is crucial for proper diagnosis and management. Management typically involves risk stratification and may include observation for asymptomatic patients, medication for symptomatic patients, or catheter ablation of the accessory pathway for definitive treatment 1. Patients with WPW should avoid AV nodal blocking agents, as these medications can potentially increase conduction through the accessory pathway and precipitate dangerous ventricular arrhythmias 1.
From the Research
EKG Changes in Wolff-Parkinson-White Syndrome
The Wolff-Parkinson-White (WPW) syndrome is characterized by specific electrocardiographic (EKG) features, including:
- A PR interval less than 0.12 seconds 2
- A slurring of the initial segment of the QRS complex, known as a delta wave 2, 3
- A QRS complex widening with a total duration greater than 0.12 seconds 2
- Secondary repolarization changes reflected in ST segment-T wave changes that are generally directed opposite (discordant) to the major delta wave and QRS complex changes 2
Diagnostic Considerations
The diagnosis of WPW syndrome relies on the presence of these EKG features, which may not always be present in cases of intermittent preexcitation 3, 4. It is essential to maintain a high index of suspicion for intermittent preexcitation and to promptly obtain an ECG after the termination of any tachyarrhythmia 3.
Risk Stratification and Management
Patients with WPW syndrome are at risk of developing supraventricular tachyarrhythmias, which can cause disabling symptoms and, in extreme cases, sudden cardiac death 2, 5, 6. The management of WPW syndrome involves risk stratification, with invasive evaluation recommended for asymptomatic patients where pre-excitation clearly does not disappear during exercise testing 4. Antiarrhythmic prophylaxis and catheter ablation of the accessory pathway may be considered in patients with previous episodes of atrial fibrillation with rapid ventricular response or frequent episodes of re-entrant tachycardias 5.