ORLANDO, Fla., Nov. 7 Astellas Pharma US, Inc. todayannounced that the investigational agent vernakalant hydrochloride increasedconversion to normal heart rhythm (sinus rhythm, or SR) in patients withatrial fibrillation (AF) following coronary artery bypass graft (CABG) orvalvular surgeries. AF is a potentially serious condition characterized by anirregular heart rhythm and a high heart rate. The study results werepresented today at the annual meeting of the American Heart Association.
"Postoperative AF is common after cardiac surgery, occurring in up to40% of patients and has a significant effect on both the intensive care unitand overall hospital length of stay," said Peter Kowey, MD, William WikoffSmith Chair in Cardiovascular Research at the Main Line Health System. "Thisstudy shows that vernakalant may be an effective treatment option forconverting AF to SR following CABG or valvular surgeries."
The Atrial arrhythmia Conversion Trial or ACT II was a randomized,double-bind, placebo-controlled, parallel-group, multinational, multicenterstudy evaluating the efficacy and safety of vernakalant among patients whoexperienced AF or atrial flutter within 24 hours to 7 days after cardiacsurgery.
Patients received vernakalant 3 mg/kg (n=107) or placebo (n=54) infusedover 10 minutes. After 15 minutes, a second 10 minute infusion of vernakalant2 mg/kg or placebo was given if AF or atrial flutter was present. The primaryefficacy measure was the percentage of patients with treatment-inducedconversion of AF/atrial flutter to SR for at least one minute within90 minutes.
Patients demonstrating conversion within 90 minutes were categorized asresponders. Other efficacy measures included time to conversion of allresponders and percentage of AF patients demonstrating conversion to SR within90 minutes for . one minute.
Following CABG or valvular surgery, a significantly higher percentage ofpatients with AF/atrial flutter given vernakalant (45 percent) demonstratedconversion to SR within 90 minutes compared to patients given placebo (15percent), p=.0002. In the subset of patients with AF at baseline, conversionwas observed in 47 percent treated with vernakalant compared with 14 percentgiven placebo, p=.0001. Median time to conversion among vernakalantresponders was 12 minutes and SR was maintained for patients with AF/atrialflutter for 24 hours in 60 percent and for seven days in 57 percent.Seventy-five percent of vernakalant responders required only one dose of drug.Vernakalant is not effective in atrial flutter.
The most common adverse events (AEs) in patients given vernakalant were AF(20 percent), nausea (6 percent), constipation (5 percent), weight increase(5 percent) and dyspnea (5 percent). Rates of serious AEs over the entirestudy were similar with placebo (11 percent) and vernakalant (9 percent). Inthe first 24 hours, only 2 patients (2 percent) given vernakalant experienceda serious AE (complete AV block and hypotension). There were no deaths orcases of torsade de pointes.
About Atrial Fibrillation
AF is an interruption of the normal sinus rhythm (arrhythmia) of the heartin which the atria, the two uppermost chambers of the heart, beat irregularlyand at an extremely rapid rate(1). During AF, rapid and uncoordinatedelectrical discharges are generated by the heart's natural pacemaker(sinoatrial node) and other parts of the atria. This causes ineffectivecontractions of the atria and reduces the ability of the heart to pump bloodthrough the body. Symptoms include dizziness, heart palpitations, weakness,shortness of breath and angina (chest pain)(1). The number of AF patients isexpected to triple over the next 50 years due to the increased prevalence ofrisk factors including hypertension, obesity, diastolic dysfunction,inflammation, diabetes and sleep apnea(2).