A medical device is provided that comprises a lead assembly configured to be at least partially located proximate to the heart. The lead assembly includes an extra-cardiac (EC) electrode to be positioned proximate to at least one of a superior vena cava (SVC) and a left ventricle (LV) of a heart. The lead assembly includes a subcutaneous remote-cardiac (RC) electrode configured to be located remote from the heart such that at least a portion of the greater vessels are interposed between the RC electrode and the EC electrode to establish an extra-cardiac impedance (ECI) vector. The processor module measures extra-cardiac impedance along the ECI vector to obtain ECI measurements. The processor module assesses a hemodynamic performance based on the ECI measurements.