ATI-2042 is being developed as an alternative to amiodarone, which is considered a first-line therapy for patients with atrial fibrillation and is known to have serious side effects. ATI-2042 was designed to have a reduced plasma half-life and a lower volume of distribution, which is expected to result in an improved safety profile. In contrast to amiodarone, ATI-2042 undergoes rapid metabolism via plasma and tissue esterases, which may reduce tissue accumulation and toxicity. The current trial will determine if ATI-2042 retains the efficacy profile of amiodarone without the side effects attributable to tissue accumulation seen with long-term dosing.