What is the significance of delta waves on an electrocardiogram (EKG)?

From the Guidelines

Delta waves on an EKG are a significant finding that requires further evaluation, particularly with an electrophysiology study, to assess the risk of arrhythmic events and guide treatment, which may include catheter ablation, as recommended by the 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1.

Key Considerations

• Delta waves represent abnormal electrical activity in the heart, commonly seen in Wolff-Parkinson-White syndrome, where an accessory pathway allows electrical signals to bypass the normal conduction system.
• The presence of delta waves on an EKG indicates a pre-excitation pattern, where part of the ventricle is activated earlier than normal through the accessory pathway.
• Further cardiac evaluation, typically with an electrophysiology study, is necessary to assess the risk of arrhythmic events and guide treatment.

Treatment Options

• Observation, without further evaluation or treatment, is reasonable in asymptomatic patients with pre-excitation, as most observational cohort studies suggest a benign course with few clinically significant arrhythmic events occurring over time 1.
• Catheter ablation of the accessory pathway is a reasonable treatment option in asymptomatic patients with pre-excitation, particularly if an EP study identifies a high risk of arrhythmic events, including rapidly conducting pre-excited AF 1.
• Medication, such as flecainide, propafenone, or beta-blockers, may be used to control arrhythmias in patients with delta waves.

Importance of Recognition

• Recognizing delta waves is crucial because patients with this finding may be at risk for dangerous arrhythmias, particularly atrial fibrillation that conducts rapidly through the accessory pathway, potentially leading to ventricular fibrillation.
• The 2017 international recommendations for electrocardiographic interpretation in athletes also highlight the importance of evaluating ventricular pre-excitation, including delta waves, to assess the risk of arrhythmic events in athletes 1.

From the Research

Onda Delta EKG

• The Wolff-Parkinson-White (WPW) syndrome is a pre-excitation syndrome characterized by a short PR interval, a prolonged QRS interval, and an initial slurring of the QRS complex called a delta wave on the ECG 2.
• The delta wave is a key feature of the WPW syndrome and is caused by the presence of accessory atrioventricular conduction fibers, known as the Kent bundle 2.
• The WPW syndrome can present with a wide spectrum of symptoms, ranging from mild palpitations to unstable tachydysrhythmias and sudden cardiac death 2.
• The diagnosis of WPW syndrome is typically made based on the presence of a delta wave on the ECG, and the treatment options include medical therapy, catheter ablation, and surgical ablation 3, 4.
• Flecainide is a useful drug for the acute and chronic control of tachycardia in WPW syndrome, and it has been shown to be effective in blocking conduction across the accessory pathway and preventing clinical recurrences 5, 6.

Treatment Options

• Catheter ablation is a highly effective and safe therapy for patients with symptomatic WPW syndrome, and it is considered the first-line therapy for these patients 3.
• Surgical ablation is typically reserved for patients who are not candidates for catheter ablation or who have failed catheter ablation 4.
• Medical therapy, including flecainide and other antiarrhythmic drugs, can be used to control symptoms in patients with WPW syndrome, but it is not always effective and can have significant side effects 5, 6.

Diagnosis and Risk Stratification

• The diagnosis of WPW syndrome is typically made based on the presence of a delta wave on the ECG, and the risk stratification is based on the presence of symptoms and the results of electrophysiological testing 3, 2.
• Patients with asymptomatic WPW syndrome may require invasive risk stratification and possible catheter ablation for important social or professional reasons 3.
• The risk of sudden cardiac death is higher in patients with symptomatic WPW syndrome, and these patients should be treated aggressively to prevent this complication 2, 5.