Flecainide monoacetate S isomer is a pharmaceutical compound used in the treatment of cardiac arrhythmias. However, there are several synonyms for this compound that are commonly used in medical literature. One such synonym is (±)-1-(2-piperidylmethyl)-2,5-benzoxazolylacetonitrile acetate (S)-2-hydroxypropanoate. This lengthy chemical name is typically shortened to just "flecainide S-isomer" in clinical discussions. Another synonym is flecainide monacetate (S) isomer, which is a more concise form of the original compound name. Regardless of the name used, it refers to the same active ingredient used to manage irregular heart rhythms and stabilize cardiac function in patients.