A NEW DOSING REGIMEN FOR ESMOLOL TO TREAT SUPRAVENTRICULAR TACHYARRHYTHMIA IN CHINESE PATIENTS

Objectives. The purpose of this study was to find a safe dosing regimen for esmolol infusion to rapidly control supraventricular tachyarrhythmia after cardiac surgery in Chinese patients. Background. Tachycardia increases cardiac work but reduces myocardial perfusion. Thus, in the critical period immediately after cardiac surgery, tachycardia itself warrants urgent intervention. Esmolol, an ultrashort-acting beta-adrenergic blocking agent, has been reported in western published reports to have good results and few side effects in the treatment of supraventricular tachyarrhythmia. However, its clinical application in Chinese patients has not yet been reported. Methods. When supraventricular tachyarrhythmia with a rapid ventricular response (>110/min) was found early after cardiac surgery, esmolol infusion with a different dosing regimen was used to control the tachyarrhythmia. Results. With the dosing regimen recommended in western published reports (repeated loading infusion with stepwise increment), acute hypotension with systolic pressure <80 mm Hg occurred in all six patients after 1 min of loading infusion of esmolol (500 mu g/kg body weight per min). To avoid the aforementioned complications, a new dosing regimen was constructed. The initial infusion rate of esmolol was set at 150 or 100 mu g/kg per min, depending on the patient's age and blood pressure. When the desired heart rate was achieved, the initial infusion rate was reduced to the maintenance infusion rate to maintain the therapeutic effect [Maintenance infusion rate = Initial infusion rate x (1 - e(-0.077t)), where t is the time period in minutes required by the initial infusion of esmolol to achieve the therapeutic effect]. With this new dosing regimen, tachycardia in most patients (9 of 11) could be controlled within 10 min, and no one experienced the side effect of hypotension. The maintenance infusion rate of esmolol needed to control supraventricular tachyarrhythmia in our patients was only 73 +/- 42 mu g/kg per min (mean +/- SD), much less than that noted in western reports. Conclusions. The dosing regiment for esmolol infusion recommended in western studies is not suitable for Chinese patients. In this report we propose a new dosing regimen for esmolol infusion that is both safe and rapid in the treatment of supraventricular tachyarrhythmia in Chinese patients.