Interaction between loop diuretic-associated mortality and blood urea nitrogen concentration in chronic heart failure.

OBJECTIVES: The purpose of this study was to investigate whether a surrogate for renal neurohormonal activation, blood urea nitrogen (BUN), could identify patients destined to experience adverse outcomes associated with the use of high-dose loop diuretics (HDLD). BACKGROUND: Loop diuretics are commonly used to control congestive symptoms in heart failure; however, these agents cause neurohormonal activation and have been associated with worsened survival. METHODS: Subjects in the BEST (Beta-Blocker Evaluation of Survival Trial) receiving loop diuretics at baseline were analyzed (N = 2,456). The primary outcome was the interaction between BUN- and HDLD-associated mortality. RESULTS: In the overall cohort, HDLD use (≥160 mg/day) was associated with increased mortality (hazard ratio [HR]: 1.56; 95% confidence interval [CI]: 1.35 to 1.80). However, after extensively controlling for baseline characteristics, this association did not persist (HR: 1.06; 95% CI: 0.89 to 1.25). In subjects with BUN levels above the median (21.0 mg/dl), both the unadjusted (HR: 1.59; 95% CI: 1.34 to 1.88) and adjusted (HR: 1.29; 95% CI: 1.07 to 1.60) risk of death was higher in the HDLD group. In patients with BUN levels below the median, there was no associated risk with HDLD (HR: 0.99; 95% CI: 0.75 to 1.34) and after controlling for baseline characteristics, the HDLD group had significantly improved survival (HR: 0.71; 95% CI: 0.49 to 0.96) (p interaction = 0.018). CONCLUSIONS: The risk associated with HDLD use is strongly dependent on BUN concentrations with reduced survival in patients with an elevated BUN level and improved survival in patients with a normal BUN level. These data suggest a role for neurohormonal activation in loop diuretic-associated mortality.

Recombinant glucagon-like peptide-1 increases myocardial glucose uptake and improves left ventricular performance in conscious dogs with pacing-induced dilated cardiomyopathy.

BACKGROUND: The failing heart demonstrates a preference for glucose as its metabolic substrate. Whether enhancing myocardial glucose uptake favorably influences left ventricular (LV) contractile performance in heart failure remains uncertain. Glucagon-like peptide-1 (GLP-1) is a naturally occurring incretin with potent insulinotropic effects the action of which is attenuated when glucose levels fall below 4 mmol. We examined the impact of recombinant GLP-1 (rGLP-1) on LV and systemic hemodynamics and myocardial substrate uptake in conscious dogs with advanced dilated cardiomyopathy (DCM) as a mechanism for overcoming myocardial insulin resistance and enhancing myocardial glucose uptake. METHODS AND RESULTS: Thirty-five dogs were instrumented and studied in the fully conscious state. Advanced DCM was induced by 28 days of rapid pacing. Sixteen dogs with advanced DCM received a 48-hour infusion of rGLP-1 (1.5 pmol x kg(-1) x min(-1)). Eight dogs with DCM served as controls and received 48 hours of a saline infusion (3 mL/d). Infusion of rGLP-1 was associated with significant (P<0.02) increases in LV dP/dt (98%), stroke volume (102%), and cardiac output (57%) and significant decreases in LV end-diastolic pressure, heart rate, and systemic vascular resistance. rGLP-1 increased myocardial insulin sensitivity and myocardial glucose uptake. There were no significant changes in the saline control group. CONCLUSIONS: rGLP-1 dramatically improved LV and systemic hemodynamics in conscious dogs with advanced DCM induced by rapid pacing. rGLP-1 has insulinomimetic and glucagonostatic properties, with resultant increases in myocardial glucose uptake. rGLP-1 may be a useful metabolic adjuvant in decompensated heart failure.