The Cardiorenal Syndrome: Should Change Make Us Uncomfortable?

Abstract

Cardiorenal interaction in heart failure is poorly understood. It is well established that the presence of chronic kidney disease increases mortality in patients with heart failure. Furthermore, several studies have demonstrated that worsening renal function (WRF) during the treatment of acute decompensated heart failure leads to inadequate resolution of congestion, recurrent hospitalizations, and increased mortality. Diuretics remain the mainstay of acute heart failure therapy but have been shown to contribute to the development of WRF, especially when administered in high doses. Therefore, the efforts of the heart failure community have focused on finding alternative therapies that allow freedom from congestion without precipitating WRF. Several novel therapies, including nesiritide, vasopressin antagonists, adenosine receptor antagonists, and ultrafiltration, have failed to outperform standard diuretic therapy alone when judged by this metric. Furthermore, none of these therapies have been shown to reduce mortality relative to standard treatment. Can we therefore assume that a therapy that promotes diuresis while improving renal function during acute treatment would be associated with better outcomes? The manuscript by Testani et al in this issue of the Journal of Cardiac Failure examines this question by assessing the impact of improved renal function (IRF) on mortality in 903 consecutive patients admitted to the Hospital of the University of Pennsylvania with acute decompensated heart failure. In that paper, 31% of patients experienced IRF, defined as a $20% improvement in estimated glomerular filtration rate (eGFR), at some point during their hospitalization, and 18% maintained this improvement at the time of discharge relative to admission. Surprisingly, patients with persistent IRF throughout hospitalization had a significantly increased