Renal dysfunction in congestive heart failure, pathophysiological and prognostic significance

Many congestive heart failure (CHF) patients suffer from various comorbidities, which may aggravate CHF or independently increase mortality risk. Renal failure (RF) is one of them. We defined bedside clinical, laboratory and electrocardiographic parameters characterizing CHF patients with and without concomitant RF, and analyzed their impact on mortality.

We studied symptomatic unselected consecutive furosemide-treated CHF patients hospitalized for various acute conditions. On admission, history taking, physical examination, chest x-ray, ECG and routine laboratory tests were performed. Subsequently, patients were divided into 2 subgroups, those with serum creatinine > or = 1.5 mg/dl (RF) and those with lower values. Following discharge, information concerning mortality and circumstance of death was obtained from hospital records and outpatient death certificates.

Included were 398 patients, 163 (40.9%) with RF and 235 free of RF. Prevailing in the RF subgroup were older age (mean age 75.5 vs 70.8, p < 0.001), male gender (p < 0.001), admission pulmonary edema (p = 0.007), cardiac arrhythmias (p = 0.05), cardiac conduction disturbances (p = 0.002), severe CHF (p = 0.005), lower ejection fraction (p = 0.03), anemia (p = 0.009), higher furosemide maintenance dosages (p < 0.001), insulin treatment (p = 0.03) and receiving less ACE inhibitors (p = 0.006). On median follow-up of 43 months, mortality was 54.9% in the RF vs 31.9% in the non-RF subgroup (p < 0.001), RF being the parameter most significantly associated with low survival (OR 1.97, p < 0.001). In the RF subgroup older age (p < 0.02), female gender (p < 0.003) and not using ACE inhibitors (p = 0.04) or drugs with antiarrhythmic effects (p < 0.005), emerged significantly associated with low survival, while diabetes mellitus (DM) and admission pulmonary edema tended to be so associated (p < 0.2). Using multivariate analysis in the RF subgroup, older age, female gender and DM proved most significantly associated with poorer survival (p = 0.004, OR 1.5, p = 0.03, OR 1.72, p = 0.04, OR 1.28, respectively). In the non-RF subgroup, only older age (p = 0.005) and DM (p = 0.05) were significantly associated with low survival. Sudden death occurred in 21 patients, 14 (8.6%) in the RF and 7 (3%) in the non-RF subgroup (p < 0.001).

RF is a marker of severity in CHF. Its full-blown deleterious prognostic effect is already manifested at serum creatinine 1.5 mg/dl. Older age, DM and female gender most significantly heralded a shorter survival. Such patients require special care.