186 VOL. 12 NO. 4 2011 REVIEWS IN CARDIOVASCULAR MEDICINE DISEASE STATE REVIEW Clinical Impact of Renal Dysfunction in Heart Failure Alberto Palazzuoli, MD, PhD, 1 Matteo Beltrami, MD, 1 Savina Nodari, MD, 2 Peter A. McCullough, MD, MPH, FACC, FACP, FAHA, FCCP, 3 Claudio Ronco, MD 4 1 Department of Internal Medicine, Cardiology Section, Santa Maria alle Scotte Hospital, Siena, Italy; 2 Department of Cardiology, University of Brescia, Italy; 3 St. John Providence Health System, Providence Park Heart Institute, Novi, MI; 4 Department of Nephrology, San Bortolo Hospital, Vicenza, Italy Renal impairment in heart failure (HF) patients has been increasingly recognized as an independent risk factor for morbidity and mortality. In the most recent European and American guidelines for HF management, renal dysfunction was considered an index of poor prognosis independent of the presence of other traditionally investigated risk factors. Different mechanisms appear to be implicated in worsening renal function in patients with acute decompensated HF (ADHF) in contrast to chronic HF. In patients with acute ADHF, renal impairment has been attributed to renal hypoperfusion due to reduced cardiac output and decreased systemic blood pressure. In these patients, neurohormonal activation of the renin-angiotensin and sympathetic nervous systems plays a key role. In chronic and clinically stable HF, other mechanisms, including microvascular damage, oxidative stress, inflammation, and fibrosis, lead to a reduced number of functioning nephrons. Differentiating transient functional changes in renal filtration and acute renal tubular injury with loss of functioning nephrons is a critical step in understanding cardiorenal syndromes and selection of patients for novel therapeutic approaches. [Rev Cardiovasc Med. 2011;12(4):186-199 doi: 10.3909/ricm0581] © 2011 MedReviews ® , LLC Key words: Chronic kidney disease • Heart failure • Cardiorenal syndrome • Mortality H eart failure (HF) is the leading cause of hospital admissions in the elderly. In addition to its high prevalence, hospitalization for acute decompensated HF (ADHF) is associated with high rates of morbidity and mortality. The clinical presentation depends on the hemodynamic status and organ perfusion, as well as neurohormonal or toxic renal damage. 1 Acute kidney injury (AKI) has become increasingly recognized as an indepen- dent risk factor for morbidity and mortality. In most circumstances, AKI occurs on top of chronic kidney disease (CKD); this combination acts as an