Compositions and methods are disclosed for altering the binding affinity of calmodulin for ryanodine receptor 2 (RyR2). As disclosed herein, these therapeutic calmodulin (TCaM) proteins can be used to correct ryanopathies by prolonging the RyR2 refractory period. Therefore, also disclosed is a method for treating a ryanopathy-associated disease in a subject that involves administering to the subject a composition comprising a TCaM disclosed herein.