Association of Serum Phosphate with Efficacy of Statin Therapy in Hemodialysis Patients

International audienceBACKGROUND AND OBJECTIVES: Statins are less efficacious in reducing cardiovascular disease risk in patients on dialysis than in the general population. Recent experimental data showed that phosphate excess promotes cellular de novo cholesterol synthesis through 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase activation. Whether this mechanism might account for the resistance of patients on dialysis to statins has not yet been explored. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: In this post hoc analysis, we examined the efficacy of statin treatment according to serum phosphate levels in the patients on dialysis who were participants of the A Study to Evaluate the Use of Rosuvastatin in Subjects on Regular Hemodialysis: An Assessment of Survival and Cardiovascular Events (AURORA) trial using serum phosphate levels at baseline and during the trial course. We first classified the patients by groups of similar phosphate trajectories over time and tested whether phosphate as a longitudinal exposure (summarized by the identified trajectory groups) modulated the occurrence of major adverse cardiovascular events and all-cause death. We replicate the analysis in the Deutsche Diabetes Dialyze Studie (4D) trial. RESULTS: In the AURORA trial, using multivariable analysis, we found that the treatment effect of statin on major adverse cardiovascular events and all-cause death was significant and protective effects in patients with low values of serum phosphate gradually faded for higher phosphate levels >5 mg/dl. A similar lack of statin treatment efficacy for both outcomes was observed with high baseline phosphate levels (>5 mg/dl). In the 4D trial, we found a comparable but not significant trend toward losing treatment efficacy in the presence of high serum phosphate levels for both outcomes. CONCLUSIONS: Our results demonstrated the limited treatment efficacy of statins in patients on dialysis in the presence of hyperphosphatemia. Copyrigh

Pathophysiological Pathways in Patients with Heart Failure and Atrial Fibrillation

Aims: Atrial fibrillation (AF) and heart failure (HF) are two growing epidemics that frequently co-exist. We aimed to gain insights into underlying pathophysiological pathways in HF patients with AF by comparing circulating biomarkers using pathway overrepresentation analyses. Methods and Results: From a panel of 92 biomarkers from different pathophysiological domains available in 1,620 patients with HF, we first tested which biomarkers were dysregulated in patients with HF and AF (n = 648) compared with patients in sinus rhythm (n = 972). Secondly, pathway overrepresentation analyses were performed to identify biological pathways linked to higher plasma concentrations of biomarkers in patients who had HF and AF. Findings were validated in an independent HF cohort (n = 1,219, 38% with AF). Patient with AF and HF were older, less often women, and less often had a history of coronary artery disease compared with those in sinus rhythm. In the index cohort, 24 biomarkers were upregulated in patients with AF and HF. In the validation cohort, 8 biomarkers were upregulated, which all overlapped with the 24 biomarkers found in the index cohort. The strongest up-regulated biomarkers in patients with AF were spondin-1 (fold change 1.18, p = 1.33x10−12), insulin-like growth factor-binding protein-1 (fold change 1.32, p = 1.08x10−8), and insulin-like growth factor-binding protein-7 (fold change 1.33, p = 1.35x10−18). Pathway overrepresentation analyses revealed that the presence of AF was associated with activation amyloid-beta metabolic processes, amyloid-beta formation, and amyloid precursor protein catabolic processes with a remarkable consistency observed in the validation cohort. Conclusion: In two independent cohorts of patients with HF, the presence of AF was associated with activation of three pathways related to amyloid-beta. These hypothesis-generating results warrant confirmation in future studies. Translational Perspective: Using an unbiased approach, we identified and validated dysregulation of three amyloid-beta related pathways in patients who had heart failure (HF) with concomitant atrial fibrillation (AF). Amyloid-beta depositions are a hallmark of Alzheimer’s disease, but might also play a role in pathophysiological processes outside the central nervous system. Biopsy studies are needed to confirm the pathophysiological role of amyloid-beta in patients with AF and HF. Diagnostic and therapeutic implications should be investigated in the light of potential pathophysiological overlap between the three aging-related epidemics: Alzheimer’s disease, AF and HF