Comparisons Of Sotalol And Amiodarone On Exercise Electrocardiology And Physiology In Patients Withous Structural Heart Disease

Introduction As a result of numerous experimental and clinical studies, the class If/Ill drugs, sotalol and amiodarone, do exert antifibrillatory action in preventing the occurrence of ventricular tachycardia (VT) and ventricular fibrillation (VF), thereby reducing sudden arrhythmic death and prolonging survival. These should now be viewed as the first-line drugs for these arrhythmias, especially in structural heart disease. Sotalol and amiodarone prolong the action potential duration of myocardial cells, resulting in a lengthening of the repolarization process and the effective refractory period. Electrophysiologic study (EPS) shows that sotalol抯 effects on repolarization are associated with reverse use dependency, which means the effect of antiarrhythmic agents causing a prolongation of the action potential duration became attenuated at faster cycle length. A lot of studies have been made to compare the electrophysiologic, electropharmacologic and clinical effects of sotalol and amiodarone. But the comparison of sotalol and amiodarone on exercise electrophysiologic effects and security has not been reported. Clinical studies prove exercise testing can be used to investigate electrophysiologic, clinical effect and security of antiarrhythmic agents. This study design to compare the electrocardiography and hemodynamic effects of sotalol and amiodarone under 6 exercise test. The objective is the comparison of sotalol and amiodarone on myocardial repolarization, intraventricular and atrioventricular conduction, double product, exercise duration, heart rate potential and exercise capacity under normal exercise, evaluating the clinical effects and security. Patients and methods Patients Entry Characteristics The study group comprised 31 consecutive patients (23 men and 8 women). These patients were referred to evaluation and treatment of infrequent premature ventricular contraction or palpitation. All patients underwent physical examination, laboratory checkup, radiography, 12-lead electrocardiogram (ECG), M-mode and two-dimensional (2-D) echocardiography, and 24-h ambulatory ECG examinations before the study to exclude possible organic heart disease and sinus node dysfunction. Patients were excluded if they had one of the following conditions: (1) manifest preexcitation or bundle-branch bolck; (2) angina or hyperfension; (3) structural heart disease as determined by M-mode and 2-D eehocardiograpliy; (4) average 24-li heart rate under 50 beats/mm, sinus pause, sinoatrial bolck, atrioventricular bolck on I-Jolter monitoring; (5) download or horizontal ST depression ~0.1mV during baseline exercise testing; (6) ventricular arrhythmias (>Lown grade I) on Holter monitoring; (7)antiarrhythmic agents have been used one week before the study; (8) systolic blood pressure under 9OmrnJ-Ig and heart rate under 60 beats/mm before the study Study Design A simple-blind and crossover study was performed on each patient. A treadmill test was performed without administration as pre-medicaton. Sotalol (80 mg per tablet) was administered twice daily for three days before the second treadmill test, performing between 2.5 and 4 ii after taking the tablet. Each subject stopped medication for four days. Amiodarone (200 mg per tablet) was administered thrice daily for one week after stopping...