The present invention relates to an antagonist of the Two-Pore Domain Potassium Channel (TASK-1) K2P3.1 for use in the prevention and/or treatment of cardiac arrhythmia in a subject. The invention also relates to a nucleic acid molecule usable in the prevention and/or treatment of cardiac arrhythmia in a subject. The invention further relates to a cell comprising said nucleic acid molecule. The invention further relates to a vector comprising said nucleic acid molecule.