Vernakalant Hydrochloride Injection Increases Conversion To Normal Heart Rhythm

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Astellas Pharma announced that the investigational agent vernakalant hydrochloride increased conversion to normal heart rhythm in patients with atrial fibrillation treated within 48 hours of the onset of symptoms. AF is a serious condition characterized by an irregular heart rhythm and a high heart rate, and frequently leads to emergency department visits. The study results were presented during the annual meeting of the American College of Emergency Physicians in Seattle.

"Most patients who develop symptoms of AF come to the emergency department within the first 48 hours," said Ian Stiell, MD of the University of Ottawa, Canada. "This analysis shows that vernakalant may provide emergency medicine physicians with an effective treatment option for managing acute AF."

AF is the most common cardiac arrhythmia, which leads to approximately 15 percent of all strokes. The number of AF patients is expected to triple over the next 50 years due to the increased prevalence of risk factors including hypertension, obesity, diastolic dysfunction, inflammation, diabetes and sleep apnea.

Study Results

The study, referred to as the atrial arrhythmia conversion trial or ACT I, was a prospective, randomized, double-blind, placebo-controlled trial of patients with symptomatic AF or nontypical atrial flutter, conducted at 44 sites in Canada, the United States, Denmark, and Sweden. This study assessed the efficacy and safety of vernakalant in converting AF lasting 3 h to <45 d to SR. The current findings are based on a sub-analysis in patients with acute AF lasting 3 to 48 h.

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A total of 161 of 356 patients (45 percent) in ACT I presented within 48 hours of AF onset. Of these, 102 patients (63 percent) received vernakalant and 59 patients (37 percent) received placebo.

Patients with AF were randomly assigned in a 2:1 ratio to vernakalant 3 mg/kg or placebo infused over 10 minutes. After 15 minutes, a second 10 minute infusion of vernakalant 2 mg/kg or placebo was given if AF persisted or atrial flutter was present. The primary efficacy measure was the percentage of patients demonstrating conversion to SR for at least one minute within 90 minutes of dosing. Patients demonstrating conversion within 90 minutes were categorized as responders. Other efficacy measures included median time to conversion and the percentage of patients still in sinus rhythm at hour 24 and day 7.

In this subanalysis, a significantly higher percentage of patients with acute AF given vernakalant (61.8 percent) demonstrated conversion to SR within 90 minutes compared to patients given placebo (5.1 percent), P<.0001. Conversion from AF to SR with vernakalant was rapid and sustained. Among vernakalant responders, median conversion time was 11 minutes, and SR was maintained for 24 h in 97 percent and for 7 days in 93 percent. Seventy-eight percent of vernakalant responders required only one dose of the drug.

The most common adverse events (AEs) in patients given vernakalant were taste disturbance (32.4 percent), sneezing (16.7 percent), nausea (15.7 percent) and dizziness (11.8 percent). The incidence of serious AEs was similar in the vernakalant and placebo treatment groups for both the entire period and the first 24 hours (11.8 percent vs. 15.3 percent and 3.9 percent vs. 1.7 percent, respectively).

About Atrial Fibrillation

Atrial fibrillation (AF) is an interruption of the normal sinus rhythm (arrhythmia) of the heart in which the atria, the two uppermost chambers of the heart, beat irregularly and at an extremely rapid rate. During AF, rapid and uncoordinated electrical discharges are generated by the heart's natural pacemaker (sinoatrial node) and other parts of the atria. This causes ineffective contractions of the atria and reduces the ability of the heart to pump blood through the body. Symptoms include dizziness, heart palpitations, weakness, shortness of breath and angina (chest pain).

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