The effects of sotalol on ventricular repolarization during exercise

Objective: Although after pacing animal and human studies have demonstrated a rate-dependent effect of sotalol on ventricular repolarization, there is little information on the effects of sotalol on ventricular repolarization during exercise. This study attempted to show the effects of sotalol on ventricular repolarization during physiological exercise. Methods: Thirty-one healthy volunteers (18 males, 13 females) were enrolled in the study. Each performed a maximal treadmill exercise test according to the Bruce protocol after random treatment with sotalol, propranolol and placebo. Results: Sotalol significantly prolonged QTc (corrected QT) and JTc (corrected JT) intervals at rest compared with propranolol (QTc 324.86 ms vs 305.21 ms, P<0.001; JTc 245.04 ms vs 224.17 ms, P<0.001) and placebo (QTc 324.86 ms vs 314.06 ms, P<0.01; JTc 245.04 ms vs. 232.69 ms, P<0.001). The JTc percent reduction increased progressively with each stage of exercise and correlated positively with exercise heart rate (r=0.148, P<0.01). The JTc percent reduction correlation with exercise heart rate did not exist with either propranolol or placebo. Conclusions: These results imply that with sotalol ventricular repolarization is progressively shortened after exercise. Thus the specific class III antiarrhythmic activity of sotalol, present as delay of ventricular repolarization, may be attenuated during exercise. Such findings may imply the need to consider other antiarrythmic therapy during periods of stress-induced tachycardia.

Ventricular Repolarization: Epidemiology and Clinical Correlates among Type-2 Diabetics with Uncontrolled Arterial Hypertension in Western Region of the Republic of Macedonia

This study aimed to describe the epidemiology of repolarization dispersion (QT dispersion and Tpeak-Tend dispersion) and further describe their associated clinical correlates among uncontrolled arterial hypertension in type-2 Diabetics patient, in western region of the Republic of Macedonia. Abnormal ventricular repolarization is associated with increased cardiovascular risk. Data relating to the frequency of increased repolarization dispersion, among uncontrolled arterial hypertension in type-2 Diabetics patient in western region of the Republic of Macedonia, are scarce. A total of 600 patients were enrolled into this observation study. Study participans were selected among primary care patient, who were receiving ongoing care for diabetes mellitus and hypertension during 1 calendar year. Twelve lead resting electrocardiography, QT, QTc, Tpeak-Tend-intervals and dispersions, were determined manually, and were compared between groups. Patients with uncontrolled BP have greater frequency of: prolonged QTc.max.interval, (61.3% vs.33.6%;p = 0.0005), prolonged Tpeak-Tend interval (65.3% vs. 34.7%;p = 0.005), increased dispersion of QTc. interval (65.9% vs. 34.1%;p = 0.00), increased disperion of Tpeak-Tend interval (65.5% vs. 34.5%;p = 0.002). Females with uncontrolled BP have greater frequency of: increased dispersion of QTc. interval (61.2% vs. 38%;p = 0.02), increased dispersion of Tpeak-Tend interval (63.1% vs. 31.5%;p = 0.008). Hypertensive diabetic patients with uncontrolled BP and abnormal ventricular repolarization have greater BMI (p = 0.000;95%CI 3.849 - 7.871), longer duration of D.M (p = 0.000;95%CI 1.600 - 1.981), longer duration of arterial hypertension (p = 0.000;95%CI 1.468 - 1.850) and less controlled glycemia (p = 0.000;95%CI 1.556 - 3.004). Frequency of increased set of electrophysiological parameters that indicate a prolonged and more heterogeneous repolarization among diabetic patients with uncontrolled BP, is considerable high and seems to be significantly associated with demographic and clinical parameters: gender, BMI, duration of diabetes, duration of BP and glycemic control.