From the Guidelines
Pre-excitation syndromes are primarily categorized into Wolff-Parkinson-White (WPW) syndrome, Lown-Ganong-Levine (LGL) syndrome, and Mahaim fiber-mediated pre-excitation, with WPW syndrome being the most common, characterized by an accessory pathway connecting the atria directly to the ventricles. These syndromes can be further classified based on the presence of manifest or concealed accessory pathways, which can conduct in the anterograde or retrograde direction, or both, and can be associated with various supraventricular arrhythmias, as noted in the 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1. Some key points about these syndromes include:
- WPW syndrome is characterized by a short PR interval and delta wave on ECG, and can cause palpitations, tachycardia, syncope, or even sudden cardiac death if they trigger arrhythmias.
- LGL syndrome features a short PR interval without delta waves, caused by accelerated conduction through the AV node or James fibers.
- Mahaim fiber pre-excitation involves accessory pathways connecting the AV node or His bundle to the ventricular myocardium, causing a normal PR interval with terminal delta waves.
- Management options include observation for asymptomatic cases, antiarrhythmic medications like beta-blockers or calcium channel blockers for symptom control, and catheter ablation for definitive treatment, especially in WPW syndrome with high-risk features or symptomatic arrhythmias, as recommended by the 2015 ACC/AHA/HRS guideline 1 and other guidelines 1. The most recent and highest quality study, the 2015 ACC/AHA/HRS guideline, provides the most up-to-date recommendations for the management of pre-excitation syndromes, and should be prioritized in clinical decision-making 1.
From the Research
Types of Pre-Excitation Syndromes
- Wolff-Parkinson-White syndrome: characterized by the presence of an accessory electrical pathway between the atria and ventricles, which can cause the heart to beat too quickly 2, 3, 4.
- Lown-Ganong-Levine syndrome: a rare condition where there is an accessory electrical pathway between the atria and ventricles, but it is located in a different area than in Wolff-Parkinson-White syndrome 3, 5, 6.
- Mahaim Fiber: a type of pre-excitation syndrome associated with a specific type of accessory pathway 2.
Characteristics of Pre-Excitation Syndromes
- Short PQ interval: a characteristic feature of pre-excitation syndromes, where the time between the onset of the P wave and the start of the QRS complex is shorter than normal 3, 5.
- Delta wave: a slurred upstroke at the beginning of the QRS complex, which is a hallmark of Wolff-Parkinson-White syndrome 5, 6.
- Abnormal atrial depolarization: pre-excitation syndromes can cause changes in the pattern of atrial depolarization, which can be detected on an electrocardiogram (ECG) 6.
Diagnosis and Management
- Electrocardiogram (ECG): a crucial diagnostic tool for detecting pre-excitation syndromes, which can show characteristic changes such as a short PQ interval and delta wave 3, 5, 4.
- Transesophageal electrostimulation: a technique used to study the electrical properties of the heart and diagnose pre-excitation syndromes 5.
- Radiofrequency ablation: a treatment option for pre-excitation syndromes, which involves destroying the accessory electrical pathway using radiofrequency energy 5.