The usual aim of treatment for patients with symptomatic paroxysmal or recent-onset
atrial fibrillation, including after cardiac surgery, is to slow the heart rate. Electrical and
drug (
amiodarone)
cardioversion are other options.
Vernakalant, an
antiarrhythmic drug, has been authorised in the European Union for rapid reduction of recent-onset
atrial fibrillation. It is only available in an
injectable form.
Vernakalant has not been compared in clinical trials with treatments slowing the heart rate, or with
electrical cardioversion. The only available comparison with another antiarrhythmic agent is a clinical pharmacology study versus
amiodarone, a slow-acting
drug, based on the rate of
cardioversion at 90 minutes in 240 patients. As expected, given the brief observation period, the rate was significantly higher with
vernakalant (51.7% versus 5.2%). During clinical evaluation, 6 deaths occurred in the
vernakalant groups versus none in the other groups (placebo or
amiodarone). The main adverse effects of
vernakalant are
cardiac arrhythmias (ventricular
arrhythmia,
torsades de pointes,
bradycardia) and severe
hypotension.
Altered taste,
sneezing, paraesthesia,
nausea and
pruritus were frequent, and respiratory and neuropsychological effects were also reported. A trial in
atrial flutter was interrupted when cases of
cardiogenic shock occurred. Interactions are to be expected with drugs that prolong the QT interval, and also with drugs that lower the heart rate or the blood
potassium concentration. In practice, it is better to continue to use
amiodarone for
drug cardioversion and to avoid using
vernakalant.