A cardiac rhythm management system provides a phonocardiographic image indicative of a heart's mechanical events related to hemodynamic performance to allow, among other things, diagnosis of cardiac conditions and evaluation of therapies treating the cardiac conditions. The phonocardiographic image includes a stack of acoustic sensor signal segments representing multiple cardiac cycles. Each acoustic sensor signal segment includes heart sounds indicative of the heart's mechanical events and representations of the heart's electrical events. The diagnosis and/or therapy evaluation are performed by observing or detecting at least an occurrence of a particular heart sound related to a cardiac time interval or a trend of a particular time interval between an electrical event and a mechanical event over the cardiac time interval.