The kidney is a regulatory organ and accommodates changes in cardiac function. There is cross-talk between the kidney and the heart. In heart failure, the kidney acts as a bystander but also contributes to several maladaptive processes. The pathophysiology of worsening kidney function and its association with prognosis are discussed, as are other aspects of how worsening kidney function contributes to increased cardiovascular risk. Data suggest that morbidity and mortality reduction in people with heart failure and kidney disease requires use of a renin angiotensin system blocker, beta blocker, and mineralocorticoid receptor antagonist, as well as an SGLT 2 inhibitor.