Faculty Bibliography

AIM/OBJECTIVE:Renal dysfunction is a common comorbidity in patients with heart failure and preserved ejection fraction (HFpEF). We sought to determine whether renal dysfunction was associated with measures of cardiovascular structure/function in patients with HFpEF. METHODS:We studied 217 participants from the PARAMOUNT study with HFpEF who had echocardiography and measures of kidney function. We evaluated the relationships between renal dysfunction [estimated glomerular filtration rate (eGFR) >30 and <60 mL/min/1.73 m(2) and/or albuminuria] and cardiovascular structure/function. RESULTS:The mean age of the study population was 71 years, 55% were women, 94% hypertensive, and 40% diabetic. Impairment of at least one parameter of kidney function was present in 62% of patients (16% only albuminuria, 23% only low eGFR, 23% both). Renal dysfunction was associated with abnormal LV geometry (defined as concentric hypertrophy, or eccentric hypertrophy, or concentric remodelling) (adjusted P = 0.048), lower midwall fractional shortening (MWFS) (P = 0.009), and higher NT-proBNP (P = 0.006). Compared with patients without renal dysfunction, those with low eGFR and no albuminuria had a higher prevalence of abnormal LV geometry (P = 0.032) and lower MWFS (P < 0.01), as opposed to those with only albuminuria. Conversely, albuminuria alone was associated with greater LV dimensions (P < 0.05). Patients with combined renal impairment had mixed abnormalities (higher LV wall thicknesses, NT-proBNP; lower MWFS). CONCLUSION/CONCLUSIONS:Renal dysfunction, as determined by both eGFR and albuminuria, is highly prevalent in HFpEF, and associated with cardiac remodelling and subtle systolic dysfunction. The observed differences in cardiac structure/function between each type of renal damage suggest that both parameters of kidney function might play a distinct role in HFpEF.

PURPOSE OF REVIEW/OBJECTIVE:Left ventricular hypertrophy (LVH) is common in end-stage renal disease (ESRD) and has been advocated as a therapeutic target. We review the considerations for targeting LVH as a modifiable risk factor in ESRD. RECENT FINDINGS/RESULTS:Pathologic myocardial changes underlying LVH provide an ideal substrate for the spread of arrhythmia and may be key contributors to the occurrence of sudden death in ESRD. LVH is present in 68-89% of incident hemodialysis patients and is frequently progressive, although regression is observed in a minority of patients. Higher degrees of baseline LVH, as well as greater increases in left ventricular mass index over time, are associated with decreased survival, but whether these associations are causal remains uncertain. Several interventions, including angiotensin blockade and frequent dialysis, can reduce the left ventricular mass index, but whether this is associated with improved survival has not been definitively demonstrated. SUMMARY/CONCLUSIONS:LVH is a highly prevalent and reversible risk factor, which holds promise as a novel therapeutic target in ESRD. Interventional trials are needed to provide additional evidence that LVH regression improves survival before prevention and reversal of LVH can be definitively adopted as a therapeutic paradigm in ESRD.

BACKGROUND:Sudden cardiovascular death is increased in chronic kidney disease (CKD). Experimental CKD models suggest that angiogenesis and nitric oxide (NO) inhibitors induce myocardial fibrosis and microvascular dropout thereby facilitating arrhythmogenesis. We undertook this study to characterize associations of CKD with human myocardial pathology, NO-related circulating angiogenesis inhibitors, and endothelial cell behavior. METHODS:We compared heart (n=54) and serum (n=162) samples from individuals with and without CKD, and assessed effects of serum on human coronary artery endothelial cells (HCAECs) in vitro. Left ventricular fibrosis and capillary density were quantified in post-mortem samples. Endothelial to mesenchymal transition (EndMT) was assessed by immunostaining of post-mortem samples and RNA expression in heart tissue obtained during cardiac surgery. Circulating asymmetric dimethylarginine (ADMA), endostatin (END), angiopoietin-2 (ANG), and thrombospondin-2 (TSP) were measured, and the effect of these factors and of subject serum on proliferation, apoptosis, and EndMT of HCAEC was analyzed. RESULTS:Cardiac fibrosis increased 12% and 77% in stage 3-4 CKD and ESRD and microvascular density decreased 12% and 16% vs. preserved renal function. EndMT-derived fibroblast proportion was 17% higher in stage 3-4 CKD and ESRD (P trend = 0.02). ADMA, ANG, TSP, and END concentrations increased in CKD. Both individual factors and CKD serum increased HCAEC apoptosis (P=0.02), decreased proliferation (P=0.03), and induced EndMT. CONCLUSIONS:CKD is associated with an increase in circulating angiogenesis and NO inhibitors, which impact proliferation and apoptosis of cardiac endothelial cells and promote EndMT, leading to cardiac fibrosis and capillary rarefaction. These processes may play key roles in CKD-associated CV disease.

The lack of evidence on the effectiveness and safety of interventions in chronic dialysis patients has been a subject of continuing criticism. New technologies are often introduced into the market without having specifically studied or even included patients with advanced kidney disease. Therefore, the need to generate valid effectiveness and safety data in this vulnerable subpopulation is of utmost importance. The US Food and Drug Administration has recently placed an increased focus on safety surveillance, and sponsors must now meet this additional postmarketing commitment. In patients with ESRD, the unique data collection environment in the United States allows for creative and efficient study designs to meet the needs of patients, providers, and sponsors. The purpose of this manuscript is to review the methodological and practical aspects of the different options for postmarketing study design in this field, with critical appraisal of their advantages and disadvantages.

BACKGROUND:Reliable data regarding absolute and relative risks of death and graft failure after coronary artery bypass graft surgery (CABG) and percutaneous coronary intervention (PCI) in renal transplant patients are unavailable. METHODS AND RESULTS/RESULTS:Renal transplant patients undergoing inpatient CABG (n=1400) or PCI (n=4097) were identified from United States Renal Data System data. Cumulative incidence of nonfatal graft failure and death was reported for observed events. A Cox model with the Fine-Gray method was used to account for competing risks in assessing relative hazards. Age and race were similarly distributed; patients who underwent CABG were more likely to have acute arrhythmia and congestive heart failure but less likely to have acute myocardial infarction on index admission. In-hospital death was more frequent after CABG (5.6% versus 3.0%, P<0.001). Cumulative incidence of death, graft failure, and the combined outcome at 3 years were 23.1%, 15.4%, and 38.5% after CABG and 22.9%, 13.3%, and 36.1% after PCI, respectively. In adjusted analyses, CABG was not associated with increased risk of graft failure versus PCI during the first 6 months (hazard ratio 1.06, 95% CI 0.79 to 1.43) or from 6 to 36 months (0.98, 0.78 to 1.22). Risk of death increased after CABG during the first 3 months (1.37, 1.08 to 1.73), but decreased from 6 months on (0.76, 0.63 to 0.93). CONCLUSIONS:CABG does not appear to be associated with a difference in risk of graft failure compared with PCI in renal transplant patients. Compared with PCI, adjusted risk of early death is higher after CABG; however, mortality from 6 months on is lower.

The functional contribution of myofibroblasts in fibrosis is not well understood. Using a new genetic mouse model to track and isolate myofibroblasts, we performed gene expression profiling followed by biological validation to identify HE4 (encoding human epididymis protein 4, also known as WAP 4-disulfide core domain-2 or Wfdc2) as the most upregulated gene in fibrosis-associated myofibroblasts. The HE4 gene encodes for a putative serine protease inhibitor that is upregulated in human and mouse fibrotic kidneys and is elevated in the serum of patients with kidney fibrosis. HE4 suppresses the activity of multiple proteases, including serine proteases and matrix metalloproteinases, and specifically inhibits their capacity to degrade type I collagen. In particular, we identified two serine proteases, Prss35 and Prss23, as HE4 targets with functional relevance in kidney fibrosis. Administration of HE4-neutralizing antibodies accelerated collagen I degradation and inhibited fibrosis in three different mouse models of renal disease. Collectively these studies suggest that HE4 is a potential biomarker of renal fibrosis and a new therapeutic target.