Cardiorenal Syndromes: Advances in Determining Diagnosis, Prognosis and Therapy

The term cardiorenal syndrome (CRS) implies acute or chronic injury to the heart and kidneys that often involves a temporal sequence of disease initiation and progression. The classification of CRS is divided into five subtypes. Types 1 and 2 involve acute and chronic cardiovascular disease (CVD) scenarios leading to acute kidney injury (AKI) or accelerated chronic kidney disease (CKD). Types 3 and 4, describe AKI and CKD, respectively, leading primarily to heart failure, although, it is possible that acute coronary syndromes, stroke, and arrhythmias could be CVD outcomes in these forms of CRS. Finally, CRS type 5 describes a systemic insult to both heart and the kidneys, such as sepsis, where both organs are injured simultaneously in persons with previously normal heart and kidney function at baseline. This manuscript will summarize key issues and future opportunities in challenging patients with CRS. Because most CRS occur in patients with pre-existing myocardial disease or chronic kidney disease, we will emphasize the chronic condition which puts individuals at risk for acute events. In the setting of a hospitalization, acute CRS can occur which have been consistently associated with inpatient complications, longer lengths of intensive care unit and hospital stay, need for renal replacement therapy, rehospitalization and death. While there are several common diagnostic and therapeutic targets for the heart and kidney, there remains considerable opportunity for both in-vitro diagnostics and medicinal therapy to favorably influence the occurrence and natural history of CRS.