Atypical Antiadrenergic Effect of Refralon as a Mechanism of High Antiarrhythmic Effectiveness

We studied the effect of Refralon on the electrophysiological properties of the supraventricular myocardium against the background of adrenergic (epinephrine) influence in the zone of the pulmonary veins, the area where 50-90% of atrial arrhythmias is triggered. The experiments were carried out on isolated tissue preparations of Wistar rats. The multichannel microelectrode array technique was used to record action potentials simultaneously in the atrium and in the ostium and distal parts of the pulmonary veins. Epinephrine application (12-50 nM) led to depolarization of the resting potential and the conduction block in the distal part of the pulmonary veins. Refralon (30 μg/kg) restored the resting potential in the distal part of the pulmonary veins. Against the background of epinephrine, Refralon did not significantly change the duration of the action potential at 90% repolarization in comparison with control. At the same time, the comparison drug E-4031 against the background of epinephrine significantly increased the duration of action potential in the atrium and in the ostium of the pulmonary veins, and sotalol increased it only in the ostium. Neither E-4031, nor sotalol restored conduction in their distal part. Refralon has a biphasic effect under conditions of adrenergic stimulation: the fast component is responsible for stabilizing the resting potential in the pulmonary vein and reduces the dispersion of action potential duration in the atrium and pulmonary vein and is also quickly washed away, and the slow component is responsible for the increase of the action potential duration and is slowly washed away.

Intravenous Cavutilide for Pharmacological Conversion of Paroxysmal and Persistent Atrial Fibrillation in Patients with Heart Failure

This work aimed to study the efficacy and safety of the class III antiarrhythmic agent cavutilide (Niferidil, Refralon) for pharmacological cardioversion in patients with paroxysmal and persistent atrial fibrillation (AF) and heart failure (HF).

METHODS AND RESULTS

In this retrospective cohort study, 58 patients with stable HF (aged 69 [61;73] years, 30 males, 78% with persistent AF) and 274 patients without HF (aged 63 [57;70] years, 196 males, 56% with persistent AF) were included. The median AF duration in the group with HF was 35.5 [10.6;124] days, and that in the group without HF was 14.5 [3.6;90] days. All patients received 5-30 µg/kg cavutilide intravenously in one to four (if needed) boluses of 5-5-10-10 µg/kg at 15 min intervals. Subsequent boluses were not administered if the patient's sinus rhythm (SR) was restored or if bradycardia, QT prolongation > 500 ms or evidence of proarrhythmia was observed. Holter electrocardiogram monitoring was started before infusion and was continued for 24 h. The main criterion for an antiarrhythmic effect was sinus rhythm restoration within 24 h of the initial bolus.

RESULTS

Cavutilide converted AF to SR in 37.9% of patients with HF after bolus 1 (5 µg/kg), in 58.6% after bolus 2 (cumulative dose = 10 µg/kg), in 74% of cases after bolus 3 (cumulative dose = 20 µg/kg) and in 92.8% of cases after bolus 4 (cumulative dose = 30 µg/kg). Cavutilide was effective in 89% of cases with persistent AF with a median duration of 70.5 [30;159] days and in 92% of cases with paroxysmal AF with a median duration of 36 [24;102] h. In the group of patients without HF, the effectiveness of bolus 1 was 36.9%, that of the bolus 2 was 58%, that of the bolus 3 was 77% and that of the bolus 4 was 90.1%. Cavutilide restored SR in 90% of patients with persistent AF with a median duration of 82.5 [28;180] days and in 90% of cases with paroxysmal AF with a median duration of 50 [24;120] h. No statistically significant difference in the probability of SR restoration or the effectiveness of each bolus of cavutilide was found between patients with and without HF. The median time to restoration of SR in patients with HF was 23 [11;55] min, and that in patients without HF was 22 [10;45] min (p = 0.424). No cases of symptomatic/severe bradycardia were observed in either group. QT prolongation over 500 ms after cavutilide injection was registered in 19% of patients without HF and in 15.5% of those with HF (p = 0.58). Short runs of Torsade de pointes tachycardia occurred in one patient (0.4%) without HF after 10 µg cavutilide administration and were successfully treated with MgSO4.

CONCLUSIONS

Cavutilide demonstrated a high likelihood of AF conversion to SR in paroxysmal (92%) and persistent (89%) arrhythmia and HF. Concomitant HF and its severity do not affect the efficacy and safety of cavutilide.

Early initiation of anti-relapse antiarrhythmic therapy in patients with atrial fibrillation and flutter after pharmacological cardioversion with refralon

Aim      Evaluating the efficacy and safety of early administration of antirecurrence antiarrhythmic therapy (AAT) following restoration of sinus rhythm (SR) with refralon.Aim      Evaluating the efficacy and safety of early administration of antirecurrence antiarrhythmic therapy (AAT) following restoration of sinus rhythm (SR) with refralon.Material and methods  The study included 247 patients with atrial fibrillation/atrial flutter (AF/AFL) (142 men) who underwent pharmacological cardioversion (PCV) with refralon. A 4-step schedule of drug administration was used (successive intravenous infusions at doses of 5, 5, 10, and 10 µg/kg; maximum total dose was 30 µg/kg). Patients who recovered SR and had no contraindications were prescribed antirecurrence AAT in the early (≤24 h; n=101) or delayed (≥24 h; n=95) period. Lappaconitine hydrobromide, propafenone, and sotalol were administered orally as the antirecurrence therapy. The decision on the time of initiating ATT and the choice of the drug and its dose was taken by the attending physician individually. The safety criteria included a prolonged PQ interval >200 ms; second- or third-degree atrioventricular block; QRS complex duration >120 ms; QT prolongation >500 ms; and heartbeat pauses >3 s. The efficacy criteria included the absence of sustained recurrence of AF/AFL after initiation of AAT and the duration of hospitalization after PCV. Patients were followed up during the study until they were discharged from the hospital.Results SR was recovered in 229 (92.7 %) patients. In the group of early AAT initiation, a PQ duration >200 ms was observed in 8 (7.9 %) patients, whereas in the group of delayed AAT initiation, in 7 patients (7.4 %; p=1.000). A wide QRS complex >120 ms was recorded in 1 (1.1 %) patient of the delayed AAT initiation group and in none of the patients of the early AAT initiation group (p=0.485). Ventricular arrhythmogenic effects and QT prolongation >500 ms were not detected in any patient. Numbers of early AF recurrence did not differ in the groups of early and delayed AAT initiation: 6 (5.9 %) vs. 5 (5.3 %), respectively (p=1.000). Median duration of hospitalization after PCV was 4 days in the group of early AAT initiation and 5 days in the group of delayed AAT initiation (р=0.009).Conclusion      Early initiation of the refralon AAT does not increase the risk of drug adverse effects and reduces the duration of stay in the hospital.

Relief of persistent atypical atrial flutter: experience with the use of niferidil

An increase in life expectancy contributes to a steady growth  of diseases of the cardiovascular system. In recent years, there has been a stable increase in the prevalence  of rhythm  disturbances  in the population.  Fibrillation and atrial flutter are among  the most common  causes  of a decrease  in the quality of life and an increase in mortality. However, the effectiveness  of various methods of treatment is not absolute,  and therefore the development and introduction  of new antiarrhythmic drugs  is particularly  relevant. Thus,  the use of a class III antiarrhythmic drug  (niferidil) is of unconditional interest, and literature data describing the effectiveness  of its use for the relief of atypical atrial flutter are extremely few. The article presents a case of successful  relief of a persistent form of atypical atrial flutter in a 79-year-old patient using three consecutive intravenous injections of niferidil at a dose of 10 mcg/kg with a 15-minute interval in 19 hours after the start of therapy. The presented clinical case confirms the effectiveness of drug cardioversion with the use of niferidil and makes it possible to consider it as an alternative to electrical cardioversion  in patients with atypical atrial flutter.

Safety and Effectiveness of Pharmacologic Conversion of Atrial Fibrillation and Flutter: Results of Multicenter Trial. Part II: Assessment of Safety

Aim. We aimed to assess safety and effectiveness of class III antiarrhythmic drug Refralon for conversion of atrial fibrillation (AFib) and flutter (AFl) in post-registration trial and to compare data of primary center (National medical research center in cardiology) with data of other hospitals.

Material and Methods. We performed retrospective cohort study in 727 patients (451 enrolled in primary center and 276 enrolled in other hospitals) admitted between June 24, 2014 and June 24, 2019. Refralon was administered for conversion of AFib and AFl in intense care units in escalating doses (10-30 micrograms/kg) intravenously.

Results. Conversion of AFib and AFl into sinus rhythm was achieved in 53,6% after administration of 10 mcg/kg dose, in 73% after administration of 20 mcg/kg dose and in 91,6% after administration of Refralon in dose up to 30 mcg/kg. No mortality and no major adverse cardiac events registered in our study. Asystole >3.0 sec observed in 5% (35 of 727) of patients): in 5% (24 of 451) of patients enrolled in primary center and in 4% (11 of 276) of patients enrolled in other hospitals; 95% confidence interval (CI) [-0.09; 0.113]. Asystole> 5.0 s observed in 1.7% of patients who further required non-urgent implantation of a permanent pacemaker due to manifestations of sinus node dysfunction. Cardiac conduction disturbances (exclusively sinus bradycardia) were registered in 7% (53 of 727) patients: in 8% (37 of 451) of patients enrolled in primary center and in 6% (17 of 276) of patients enrolled in other hospitals; 95% CI: [-0.1; 0.15]. Only 0.14% of patients had symptomatic sinus bradycardia that resolved after atropine injection. Ventricular arrhythmias (exclusively Torsade de pointes tachycardia in excessive QT interval prolongation) were registered in 1.7% (12 of 727) patients: in 2% (9 of 451) of patients in primary center and in 1% (3 of 276) of patients of other hospitals; 95% CI: [-0.06; 0.08]. QTc interval prolongation to values >500 ms documented in 19% (138 of 727) of patients: in 21% (95 of 451) of patients in primary center and in 16% (43 of 276) of patients in other hospitals; 95% CI: [-0.13; 0.24].

Conclusion: In post-registration multicenter trial Refralon demonstrated good safety profile in conversion of AFib and AFl. Potential risk of TdP tachycardia mandates precautions with the use of the drug. In other hospitals Refralon did not demonstrate lower safety than in primary medical center.