Intravenous Administration of Magnesium and Potassium Solution Lowers Energy Levels and Increases Success Rates Electrically Cardioverting Atrial Fibrillation

Arian Sultan, M.D.; Daniel Steven, M.D.; Thomas Rostock, M.D.; Boris Hoffmann, M.D.; Kai Müllerleile, M.D.; Helge Servatius, M.D.; Imke Drewitz, M.D.; Jakob Lüker, M.D.; Philip Meyer; Tushar Salukhe, M.D., Ph.D.; Stephan Willems, M.D.

Disclosures

J Cardiovasc Electrophysiol. 2012;23(1):54-59. 

In This Article

Abstract and Introduction

Abstract

Intravenous Electrolytes Increase Success Rate of Cardioversion.
Background:
External biphasic electrical cardioversion (CV) is a standard treatment option for patients suffering from acute symptoms of atrial fibrillation (AF). Nevertheless, CV is not always successful, and thus strategies to increase the success rate are desirable.
Objective: The purpose of this study was to evaluate the effect of intravenously administered K/Mg solution on the biphasic CV energy threshold and success rate to restore sinus rhythm (SR) in patients with AF.
Methods: The study consisted of 170 patients with persistent AF. The patients were randomly assigned to undergo biphasic CV either with (n = 84) or without (n = 86) pretreatment with K/Mg solution. An energy step-up protocol of 75, 100, and 150 W (J) was used.
Results: Biphasic CV of AF was effective in 81 (96.4%) patients in the pretreatment and 74 (86.0%) patients in the control group (P = 0.005). The effective energy level required to achieve SR was significantly lower in the pretreated group (140.8 ± 26.9 J vs 182.5 ± 52.2 J, P = 0.02). No K/Mg-solution-associated side effects such as hypotension or bradycardia were observed.
Conclusion: Administration of K/Mg solution positively influences the success rate of CV in patients with persistent AF. Furthermore, significantly less energy is required to successfully restore SR and therefore K/Mg pretreatment may facilitate SR restoration in patients undergoing CV for AF.

Introduction

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and represents a major cardiac cause for hospitalization. Thromboembolic events, impaired left ventricular ejection fraction, and loss of atrial function are common adverse sequelae of persistent AF.[1,2]

Biphasic electrical cardioversion (CV) is a standard treatment option for patients suffering from symptomatic AF.[3] Despite its often short-term effect, its efficacy in immediate restoration of sinus rhythm (SR) has been proven. Although external electrical CV is a widely preferred CV modality, its overall immediate success rate for restoration of SR ranges from 64% to 96%.[4] This variability is likely to be related to factors such as duration of AF, electrode position, level of thoracic compression, varying energy levels, and electrolyte imbalances. Therefore, administration of electrolyte solutions containing potassium (K) and magnesium (Mg) can be used in patients undergoing CV without immediate SR restoration.

The imbalance of intracellular K and Mg levels seems to play an important role in the maintenance of AF. It has been shown that up to 20% of patients with new onset of AF have significantly lower Mg levels compared to patients without AF.[5] Clinical studies also support the observation that low plasma levels of K and Mg may be associated with occurrence of ventricular arrhythmias.[6,7]

Potassium and magnesium are two of the most important electrolytes gating ion channel transport processes and therefore regulating normal membrane excitability in myocytes. The key role of K is a fast and uniform repolarization of the myocyte during the action potential via numerous repolarizing K ion currents. Hypokalemia can lead to hyperpolarization and onset of arrhythmias. The pharmacological interactions of Mg include calcium antagonism, regulation of energy transfer, and membrane stabilization.[8] It has been demonstrated that i.v. Mg administration results in reduction of automaticity and atrioventricular nodal conduction along with a potential decrease of AF occurrence after cardiac surgery.[9,10,11]

The important role of K and Mg in maintaining electrical membrane stability, its potential cost-effectiveness and low-risk profile justify a potential interest for routine clinical use. The aim of this study was to investigate the influence of a standardized i.v. K/Mg application on success rates and energy levels required for SR restoration in patients with AF undergoing CV.

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