A multicenter observational study of the effectiveness of antiarrhythmic agents in ventricular arrhythmias: A propensity-score adjusted analysis

Population pharmacokinetic/pharmacodynamic modeling of nifekalant injection with varies dosing plan in Chinese volunteers: a randomized, blind, placebo-controlled study

Nifekalant hydrochloride is a class III antiarrhythmic agent which could increase the duration of the action potential and the effective refractory period of ventricular and atrial myocytes by blocking the K+ current. Nifekalant is used to prevent ventricular tachycardia/ventricular fibrillation. QT interval prolongation is the main measurable drug effect. However, due to the complicated dosing plan in clinic, the relationship among dosage, time, drug concentration and efficacy is not fully understood. In this study, a single-center, randomized, blind, dose-ascending, placebo-controlled study was conducted to explore the intrinsic characteristics of nifekalant injection in healthy Chinese volunteers by a population pharmacokinetic (PK)-pharmacodynamic (PD) model approach. 42 subjects were enrolled in this study and received one of three dose plans (loading dose on Day 1 (0.15, 0.3 or 0.5 mg/kg), loading dose followed by maintenance dose (0.2, 0.4 or 0.8 mg/kg/h) on Day 4) or vehicle. Blood samples were drawn for PK evaluation, and ECGs were recorded for QTc calculation at the designed timepoints. No Torsades de Pointes occurred during the study. The popPK model of nifekalant injection could be described by a two-compartment model with first-order elimination. The population mean clearance (CL) was 53.8 L/h. The population mean distribution volume of the central (Vc) and peripheral (Vp) compartments was 8.27 L and 45.6 L, respectively. A nonlinear dose-response (Emax) model well described the pharmacodynamic effect (QTc interval prolongation) of nifekalant. The Emax and EC50 from current study were 101 ms and 342 ng/mL, respectively.

Intraprocedural Conversion Efficacy of Intravenous Nifekalant Administration for Persistent Atrial Fibrillation after Pulmonary Vein Isolation

The aim of this study was to prospectively assess the efficacy, safety, and predictive effect of intravenous nifekalant administration for persistent atrial fibrillation (PerAF) after pulmonary vein isolation (PVI) with second-generation cryoballoon ablation (CBA) on 1-year atrial tachyarrhythmia (ATa) -free survival by examining the pharmacological conversion rate.One hundred and two drug-refractory, consecutive PerAF patients undergoing PVI were enrolled in this prospective observational study. After PVI, nifekalant (50 mg) was given followed by 30 minutes of observation and no further intervention. PerAF was successfully converted to sinus rhythm (SR) in 60 patients (58.8%) after a median time of 7.75 (4.13-12) minutes (group N). In the remaining 42 patients (41.2%) (group C), PerAF was successfully converted to SR by external electrical cardioversion. Nonsustained ventricular tachycardia occurred in 1 patient in group N. The left atrial volume (LAV) in group C was larger than that in group N (128.2 ± 28.2 versus 111.8 ± 24.5 mL, P = 0.002). Phrenic nerve injury occurred in 4 of 102 patients (3.9%). No other complications occurred during the procedure or within the 1-year follow-up period. At the 1-year follow-up, after a 3-month blanking period (BP), ATa-free survival during 1-year follow-up in group C was significantly lower than that in group N (50.0% versus 71.7%, P = 0.026), and the overall ATa-free survival rate was 62.7%. Two patients in group C and 4 patients in group N underwent a second procedure with radiofrequency catheter ablation. Multivariate Cox regression analysis demonstrated that unsuccessful conversion to SR (P = 0.025), ATa relapse during the BP (P = 0.000), and larger LAV (P = 0.016) were independent predictors of ATa recurrence at the 1-year follow-up.In conclusion, at the 1-year follow-up, the ATa-free survival rate after PVI with CBA for PerAF patients was 62.7%, and successful conversion to SR with nifekalant could serve as a clinical predictor of reduced ATa recurrence.

Factors associated with re-arrest following initial resuscitation from cardiac arrest

BACKGROUND

To examine patient- and arrest-level factors associated with the incidence of re-arrest in the hospital setting, and to measure the association between re-arrest and survival to discharge.

METHODS

This work represents a retrospective cohort study of adult patients who were successfully resuscitated from an initial out-of-hospital cardiac arrest (OHCA) or in-hospital cardiac arrest (ICHA) of non-traumatic origin at two urban academic medical centers. In this study, re-arrest was defined as loss of a pulse following 20min of sustained return of spontaneous circulation (ROSC).

RESULTS

Between 01/2005 and 04/2016, 1961 patients achieved ROSC following non-traumatic cardiac arrest. Of those, 471 (24%) experienced at least one re-arrest. In re-arrest patients, the median time from initial ROSC to first re-arrest was 5.4h (IQR: 1.1, 61.8). The distribution of initial rhythms between single- and re-arrest patients did not vary, nor did the median duration of initial arrest. Among 108 re-arrest patients with an initial shockable rhythm, 60 (56%) experienced a shockable re-arrest rhythm. Among 273 with an initial nonshockable rhythm, 31 (11%) experienced a shockable re-arrest rhythm. After adjusting for significant covariates, the incidence of re-arrest was associated with a lower likelihood of survival to discharge (OR: 0.32; 95% CI: 0.24-0.43; p<0.001).

CONCLUSIONS

Re-arrest is a common complication experienced by cardiac arrest patients that achieve ROSC, and occurs early in the course of their post-arrest care. Moreover, re-arrest is associated with a decreased likelihood of survival to discharge, even after adjustments for relevant covariates.