Devices and methods for detecting heart failure (HF) events or identifying patient at elevated risk of developing future HF events, such as events indicative of HF decompensation status, are described. The devices and methods can detect an HF event or predict HF risk using one or more physiologic sensor signals including an electrogram and a heart sound signal. A medical device can use the physiologic signals to calculate one more signal metrics indicative of systolic function of the heart, including relative timing between first and second signal features selected from signal features generated from the electrogram or the heart sound signals. The medical device can detect an HF event using the signal metrics, or use the signal metrics to calculate a composite risk indicator indicative of the likelihood of the patient later developing an event indicative of worsening of HF.