A method is described for reducing the likelihood of the occurrence of a cardiac arrhythmias of the type leading to sudden cardiac death in a mammalian subject. The method comprises administering to the mammalian subject an effective amount of a composition to agonize .beta..sub.3 adrenergic receptors in the mammalian subject. The composition may comprise one or more agents that are known to agonize .beta..sub.3 adrenergic receptors, such as BRL 37344, CPG 12177, CL 316243, SR 58661, pindolol, and cyanopindolol.