This is a pilot, single-center, non-invasive interventional study evaluating the performance of KV-PREDICT, an investigational diagnostic medical device (Class IIa, not CE-marked), in adult patients with heart failure. During a single scheduled outpatient visit, the device is placed externally on the chest, over clothing, and records a single-lead ECG together with cardiac mechanical vibration signals for about 10 seconds. The study assesses whether the device can acquire signals of adequate quality and reproducibility to allow extraction of mechanical and electromechanical cardiac parameters (such as systolic and diastolic time intervals and the amplitudes of mechanical vibrations corresponding to the heart sounds S1-S4). The study does not aim to support clinical decisions, does not change patient management, and does not evaluate the diagnostic or predictive performance of the device. About 120 patients across NYHA functional classes I-III and different left-ventricular function profiles will be enrolled. No direct clinical benefit to participants is expected; anticipated risks are minimal given the non-invasive, brief procedure.