Compositions and methods for increasing efficiency of cardiac metabolism

1. A pharmaceutical composition comprising a controlled-release formulation of a compound represented by formula (X):

2. The pharmaceutical composition of claim 1 , wherein the controlled-release formulation comprises the compound in a therapeutically effective amount to increase cardiac efficiency in a subject.

3. The pharmaceutical composition of claim 2 , wherein the controlled-release formulation is formulated for oral administration.

4. The pharmaceutical composition of claim 3 , wherein the controlled-release formulation comprises a format selected from the group consisting of a tablet, troche, lozenge, aqueous suspension, oily suspension, emulsion, hard capsule, soft capsule, and syrup.