Cardioversion of atrial fibrillation with ibutilide: when is it most effective?

Ibutilide with magnesium for conversion of atrial fibrillation or flutter in rheumatic heart disease patients: Ibutilide with magnesium for chemical cardioversion of atrial fibrillation or flutter

Background

Data on adjunctive use of magnesium with ibutilide for conversion of persistent rheumatic atrial fibrillation and flutter to sinus rhythm is lacking.

Aim

We aimed to study the efficacy of adjunctive supplementation of intravenous magnesium with ibutilide for conversion of persistent rheumatic atrial fibrillation and flutter to sinus rhythm and to define a definite level of serum magnesium which leads to significant increase in rates of such conversion.

Methods and results

This was a prospective study including 33 Rheumatic heart disease patients (13 males and 20 females) with mean age of 49.27 ± 11.4 years and persistent AF or AFl. All patients received intravenous magnesium to raise serum magnesium level in range of 4 mg/dl to 4.5 mg/dl prior to administration of Ibutilide. 25 out of 33 (76%) patients converted to sinus rhythm. Upon univariate analysis, presence of background beta blocker therapy, serum potassium and magnesium at time of Ibutilide injection were found to have significant relation with conversion to sinus rhythm. Upon multivariate analysis serum magnesium level at the time of Ibutilide injection was found to have significant contribution on post injection rhythm reversal (p-value = 0.006).

The level of magnesium at 3.8 mg/dl was found to have maximum sensitivity of 96% and specificity of 62.5% for conversion to sinus rhythm by ibutilide with magnesium (p-value< 0.05).

Conclusions

Ibutilide is highly effective in cardioversion of persistent rheumatic atrial fibrillation/flutter patients. Raising Serum Magnesium levels above 3.8 mg/dl significantly improves efficacy of ibutilide.

Comparison of intravenous ibutilide vs. propafenone for rapid termination of recent onset atrial fibrillation

This study was to evaluate the efficacy and safety of ibutilide and propafenone given intravenously in converting recent onset atrial fibrillation (AF). Eighty-two consecutive patients with AF (onset in 2 h to 90 days) were randomly assigned to receive two 10-min infusions, 10 min apart, of either ibutilide (1 mg) or propafenone (70 mg). The treatment was considered successful if sinus rhythm occurred within 90 min after the beginning of infusion. Ibutilide had a significantly higher rate of cardioversion than propafenone (70.73 vs. 48.78%, p = 0.043). The patients with shorter AF duration or smaller left atrium diameter had a higher success rate. Nonsustained monomorphic ventricular tachycardia was the most serious adverse effect of ibutilide in 9.76% of patients, and hypotension and heart pause were the major serious adverse events in 17.07% of patients treated with propafenone. Ibutilide is more effective than intravenous propafenone for the cardioversion of recent onset AF, and the adverse effects are rare and transient.

A randomized, controlled trial of RSD1235, a novel anti-arrhythmic agent, in the treatment of recent onset atrial fibrillation

OBJECTIVES

The purpose of this study was to determine the efficacy and safety of intravenous RSD1235 in terminating recent onset atrial fibrillation (AF).

BACKGROUND

Anti-arrhythmic drugs currently available to terminate AF have limited efficacy and safety. RSD1235 is a novel atrial selective anti-arrhythmic drug.

METHODS

This was a phase II, multi-centered, randomized, double-blinded, step-dose, placebo-controlled, parallel group study. Fifty-six patients from 15 U.S. and Canadian sites with AF of 3 to 72 h duration were randomized to one of two RSD1235 dose groups or to placebo. The two RSD1235 groups were RSD-1 (0.5 mg/kg followed by 1 mg/kg) or RSD-2 (2 mg/kg followed by 3 mg/kg), by intravenous infusion over 10 min; a second dose was given only if AF was present. The primary end point was termination of AF during infusion or within 30-min after the last infusion. Secondary end points included the number of patients in sinus rhythm at 0.5, 1, and 24 h post-last infusion and time to conversion to sinus rhythm.

RESULTS

The RSD-2 dose showed significant differences over placebo in: 1) termination of AF (61% vs. 5%, p < 0.0005); 2) patients in sinus rhythm at 30 min (56% vs. 5%, p < 0.001); 3) sinus rhythm at 1 h (53% vs. 5%, p = 0.0014); and 4) median time to conversion to SR (14 vs. 162 min, p = 0.016). There were no serious adverse events related to RSD1235.

CONCLUSIONS

RSD1235, a new atrial-selective anti-arrhythmic agent, appears to be efficacious and safe for converting recent onset AF to sinus rhythm.

Use of Ibutilide for Cardioversion of Recent-Onset Atrial Fibrillation and Flutter in Elderly

Ibutilide is a class III antiarrhythmic drug used for pharmacological cardioversion of recent-onset atrial fibrillation and flutter. The objective of the study was to assess the efficacy of ibutilide in elderly patients (age, >or=65 years). The study population consisted of 32 consecutive elderly patients (17 women, 15 men; mean age, 76 +/- 8 years; age range, 65-94 years) with recent-onset atrial fibrillation (19 patients) or flutter (13 patients). Ibutilide was administered 1-mg intravenously over 10 minutes, and a second 10-minute infusion of 1-mg was given if the arrhythmia did not terminate within 10 minutes after the end of initial infusion. Twenty-six patients received two 1-mg doses of ibutilide. The rate of successful arrhythmia termination was 59% (19 patients): 63% in patients with atrial fibrillation (12 of 19) and 54% in atrial flutter (7 of 12). The mean conversion time was 33 +/- 45 minutes. Three-fourths of the conversions occurred within 45 minutes of treatment. No clinical variables were correlated with success of cardioversion. Patients with a left atrial size of 50 mm or larger had a conversion rate of 50% compared with a conversion rate of 61% in patients with a left atrial size of less than 50 mm (P = NS). Ibutilide-induced lengthening in the QTc interval was of 17 +/- 21 milliseconds. Cardiac complications were torsade de pointes (1 patient), nonsustained ventricular tachycardia (1 patient), and transient bradycardia (1 patient). Torsade de pointes was terminated with direct current cardioversion. Ibutilide appears to be an effective drug for conversion of recent-onset atrial fibrillation and flutter in elderly patients under monitored conditions. Complications are rare and transient.

Oral class III antiarrhythmics: what is new?

PURPOSE OF REVIEW

This review describes the latest developments in the clinical usage of class III antiarrhythmics. It also discusses some new studies providing insight into the mechanism of action of these drugs.

RECENT FINDINGS

New data suggest that amiodarone is one of the most effective drugs for management of ventricular as well as supraventricular tachyarrhythmias. As over the years we have learned to deal with the toxic side effects of this drug, the risk of bradyarrhythmias requiring placement of a pacemaker is becoming more significant. Sotalol was approved for treatment of atrial fibrillation and atrial flutter (AF). It was also found to be effective in management of postoperative AF. Dofetilide has been approved for the conversion and maintenance of sinus rhythm in AF; its role in ventricular arrhythmias remains unclear. Data are emerging regarding clinical efficacy of azimilide and dronedarone.

SUMMARY

Management of arrhythmias in patients with structural heart disease remains a challenge. Class III antiarrhythmics are the mainstay of treatment in this group of patients.