Amiodarone--efficacy and late potentials during long-term therapy

Area of Science:

• Cardiology
• Electrophysiology
• Pharmacology

Background:

• Amiodarone is a potent antiarrhythmic drug used for ventricular arrhythmias.
• Signal-averaged ECG (SAECG) and Holter monitoring are key diagnostic tools in arrhythmia assessment.
• Assessing the impact of amiodarone on SAECG parameters and its correlation with Holter data is clinically relevant.

Purpose of the Study:

• To investigate the long-term effects of amiodarone on signal-averaged ECG parameters.
• To evaluate the relationship between signal-averaged ECG findings and Holter monitoring data during amiodarone therapy.
• To assess amiodarone's efficacy in patients with refractory ventricular arrhythmias.

Main Methods:

• Prospective study design involving 27 patients with dilated cardiomyopathy or coronary heart disease and high-grade ventricular arrhythmias.
• Patients were treated with amiodarone after failure of multiple Class I antiarrhythmic drugs.
• Serial ECG, signal-averaged ECG, and 24-hour Holter monitoring were performed before and during amiodarone therapy.

Main Results:

• A significant increase in the total filtered QRS complex duration was observed with amiodarone treatment.
• The incidence of late potentials on signal-averaged ECG remained stable.
• Holter monitoring indicated a responder rate of 46-81% to amiodarone therapy.
• No significant correlation was found between signal-averaged ECG parameters and Holter monitoring results.

Conclusions:

• Long-term amiodarone therapy leads to significant changes in QRS duration on signal-averaged ECG.
• Amiodarone demonstrates a substantial responder rate for ventricular arrhythmias as assessed by Holter monitoring.
• Signal-averaged ECG and Holter monitoring provide complementary, but not directly correlated, information in patients on amiodarone.