1. A cardiac rhythm management system comprising: a cardiac lead adapted to be delivered to a target location within a coronary vein having an inner wall, the cardiac lead including: an elongated lead body including a distal end; at least one electrode coupled to the lead body; and at least one conductor extending within the lead body operatively coupled to the at least one electrode; a strain sensing element coupled to the distal end of the lead body, the strain sensing element configured to radially expand against and frictionally engage the inner wall of the coronary vein, and further configured to generate an output signal indicative of changes in a localized inner dimension of the coronary vein during a cardiac cycle; and a pulse generator including a processor operatively coupled to the strain sensing element, the processor configured to receive the output signal from the strain sensing element and to estimate a measure of hemodynamic performance therefrom.