Methods are described for using compositions containing platelet-rich plasma for the treatment of acute or chronic dysfunction of cardiac muscle. The method may employ a kit which includes a platelet-rich plasma composition and a pH adjusting agent and a catheter or syringe for delivery of the platelet-rich plasma composition to dysfunctional cardiac muscle. The kit may also include a syringe for withdrawing blood from a patient and a centrifuge device means to obtain platelet-rich plasma.