A cardiac harness is configured to fit about a portion of a patient's heart so as to exert a compressive force on the heart during at least a portion of the cardiac cycle. The harness can be constructed of a plurality of individual modules assembled ex vivo or in vivo. The modules can have different physical characteristics, such as having different compliance, and may or may not include spring hinges. Portions of a cardiac harness can be connected to each other using a coupling mechanism such as, for example, a zip coupler.