The many NO's to the use of class I antiarrhythmics: does this also apply to ethacizinum?

Abstract Introduction Diaethyl-amino-propyonylaethoxy-carbonyl-amino-phenothiazinum known by brand name Ethacizinum, Ethacizine, Ethacyzin is a unique domestic Ic antiarrhythmic drug. The main reported common for Ic class undesirable effects of the drug are the negative inotropic effect and QT interval prolongation. Most patients with atrial fibrillation (AF) require maintenance antiarrhythmic therapy after restoration of sinus rhythm (SR). The results of clinical experience with the use of ethacizinum indicate the possibility of increasing the effectiveness and safety of drug-induced maintenance of SR after electrical cardioversion (ECV) of AF, which became the basis for this work. Purpose To study the possibilities of increasing the efficiency and safety of cardioversion of persistent form of AF using an antiarrhythmic drug of the Ic antiarrhythmic class medication – ethacizinum. Methods In an open-label, one-center Latvian Centre of Cardiology prospective study patients with peristent AF received Ic class medications - propaphenone (300mg twice/daily) or aethacizinum (100mg/day) for 6 months after ECV and restoration of SR. For evaluation of safety parameters rest electrocardiogram (ECG), bicycle-exercise test, transthoracic echocardiography, bloos tests as complete blood count, clinical biochemistry (including BNP level, electrolytes), 24-hour Holter monitoring were performed at inclusion and during follow-up. Results Of the 62 patients enrolled in the study, 57 completed it per protocol. The mean age of patients completed the study was 62.56 ± 6.77 years, 36.8 % were males and in 86% sinus rhythm after ECV maintained. Recurrence rate of AF in ethacizinum group showed close to statistically significant superiority compared to propafenone (55.6% vs 72.5%) (p=0.05). LV ejection fraction 55 ± 5% vs 54 ± 4% (p=0.81) showed minor changes. None of the patients experienced major adverse events, no significant changes in blood count or biochemistry and ECG, stress-test or Holter parameters were observed in per protocol group. Conclusions Class IC antiarrhythmic drug ethacizinum do not affect the duration of the QT interval, inotropic myocardial function and can potentially be prescribed immediately after restoration of SR, which may contribute to more effective prevention of early recurrences of AF and a reduction in number of hospitalization of patients. The observed safety provides the rationale for a larger, double-blind controlled study in different daily dosage.