Congestion is the hallmark and the main therapeutic target in patients with decompensated heart failure (HF). Residual clinical congestion is defined as a high left ventricular diastolic pressure associated with signs and symptoms of HF, such as dyspnoea, rales and oedema, persisting despite guideline-directed medical treatment. Residual congestion in the predischarge and early post-discharge phase is the major risk factor for HF readmission and mortality. Therefore, prompt recognition of congestion and rapid optimisation of medical and device therapy are crucial to induce remission in this malignant process. In this paper we discuss the definitions, prevalence and prognosis of HF decompensation; the significance of assessing residual congestion in HF patients; the results of observational and randomised clinical trials to detect and treat residual congestion; and the current guidelines to prevent recurrent HF decompensation in the context of residual congestion. Strategies to detect and address residual congestion are crucial to stopping readmissions after an acute HF hospitalisation and improving long-term prognosis.