Described herein are peptibodies that can contain a TertiapinQ peptide, formulations thereof, and uses thereof. In some embodiments, the peptibody can include a first monomer and a second monomer, wherein each monomer can include an Fc polypeptide, a first TertiapinQ peptide, wherein the N-terminus of the first TertiapinQ peptide can be linked to the C-terminus of the Fc polypeptide via a first linker, and wherein the first monomer and the second monomer can be attached via a disulfide bridge between the Fc polypeptide of the first monomer and the Fc polypeptide of the second monomer. The compositions and formulations thereof can be used to treat atrial fibrillation.
