Importance:The cornerstones of imaging in heart failure (HF) are the measurement of systolic and diastolic function and left ventricular (LV) filling pressure. Observations:Ejection fraction and the assessment of LV filling pressure and diastolic dysfunction using the ratio of early transmitral flow and LV relaxation (E/e') are conventional imaging markers of LV function. Despite their extensive use in HF guidelines, both have significant detractions, especially in an era when HF with preserved ejection fraction is becoming the dominant presentation. In contrast, strain imaging has provided a new window into myocardial mechanics. Myocardial strain is now well validated, robust, and can easily be performed on most modern echocardiography machines. This Review summarizes the evidence in 9 situations across the stages of HF where LV global longitudinal strain and other strain parameters may provide information on risk prediction, diagnosis, assessment of treatment response, and follow-up. Conclusions and Relevance:The evolution of myocardial deformation imaging from research tool to clinical practice will provide clinicians with a useful additional imaging parameter to facilitate the assessment and risk evaluation of patients with HF.