Signal-averaged electrocardiogram for evaluation of recurrent syncope

Area of Science:

• Cardiology
• Electrophysiology

Background:

• Syncope evaluation requires accurate diagnosis of underlying causes, particularly serious ventricular arrhythmias.
• Signal-averaged electrocardiography (SAECG) is a noninvasive technique to detect delayed ventricular potentials, often associated with VT.

Purpose of the Study:

• To assess the diagnostic role of SAECG in identifying ventricular tachycardia (VT) in patients presenting with syncope.
• To evaluate the prognostic value of SAECG in predicting long-term outcomes, including mortality and syncope recurrence.

Main Methods:

• Signal-averaged ECG was performed on 150 consecutive syncope patients.
• Patients underwent a standardized protocol to determine syncope etiology.
• Late potentials on SAECG were correlated with VT diagnosis and patient outcomes during follow-up.

Main Results:

• SAECG identified late potentials in 16 of 22 VT patients (sensitivity 73%) and was normal in 101 of 114 non-VT patients (specificity 89%).
• Predictive accuracy was 55% overall, increasing to 82% in patients with coronary artery disease.
• Absence of late potentials indicated a low incidence of VT.
• No significant difference in survival or syncope recurrence was observed between patients with and without late potentials.

Conclusions:

• Signal-averaged ECG is a valuable noninvasive tool for identifying patients with serious ventricular arrhythmias among unselected syncope patients.
• SAECG's ability to predict long-term prognosis in this cohort was limited, despite its diagnostic utility for VT detection.