Hyperuricaemia predicts poor outcome in patients with mild to moderate chronic heart failure

Novel Oxidative Stress Biomarkers with Risk Prognosis Values in Heart Failure

Oxidative stress (OS) is mediated by reactive oxygen species (ROS), which in cardiovascular and other disease states, damage DNA, lipids, proteins, other cellular and extra-cellular components. OS is both initiated by, and triggers inflammation, cardiomyocyte apoptosis, matrix remodeling, myocardial fibrosis, and neurohumoral activation. These have been linked to the development of heart failure (HF). Circulating biomarkers generated by OS offer potential utility in patient management and therapeutic targeting. Novel OS-related biomarkers such as NADPH oxidases (sNox2-dp, Nrf2), advanced glycation end-products (AGE), and myeloperoxidase (MPO), are signaling molecules reflecting pathobiological changes in HF. This review aims to evaluate current OS-related biomarkers and their associations with clinical outcomes and to highlight those with greatest promise in diagnosis, risk stratification and therapeutic targeting in HF.

Serum Uric Acid and Risk of Chronic Heart Failure: A Systematic Review and Meta-Analysis

Objectives: A systematic review and meta-analysis was performed to evaluate the potential prognostic role of serum uric acid (SUA) in patients with chronic heart failure (CHF).

Methods: The Embase, PubMed, Web of Science and Cochrane Library databases were searched up to 5 April 2021 for relevant publications. Random effects model was used to pool data. STATA15.0 software was used to perform meta-analysis. Heterogeneity was assessed using the Cochran Q statistic (significance level of P < 0.10) and I² statistics (significance level of 50%).

Results: Ultimately, 18 publications reporting adverse events in CHF patients were included. The results indicate reveal associations between a high level of SUA and the risk of all-cause mortality (HR 2.24, 95% CI 1.49–3.37), cardiovascular mortality (HR 1.14, 95% CI 1.06–1.23), and the composite of death or cardiac events (HR 1.26, 95% CI 1.01–1.56) in CHF patients. A 1 mg/dL increase in serum uric acid led to 4% (HR 1.04, 95% CI 1.02–1.05) and 9% (HR 1.09, 95% CI 1.03–1.17) increases in the risk of all-cause mortality and the composite endpoint of death or cardiac events in CHF patients, respectively.

Conclusion: Serum uric acid is positively associated with the risk of adverse events in CHF patients. This study protocol has been registered at PROSPERO as CRD42021247084 (https://www.crd.york.ac.uk/PROSPERO).

Systematic Review Registration:https://www.crd.york.ac.uk/PROSPERO.

Comparison between febuxostat and allopurinol uric acid-lowering therapy in patients with chronic heart failure and hyperuricemia: a multicenter randomized controlled trial

Objective

Heart failure (HF) is a common and highly morbid cardiovascular disorder. Oxidative stress worsens HF, and uric acid (UA) is a useful oxidative stress marker. The novel anti-hyperuricemic drug febuxostat is a potent non-purine selective xanthine oxidase inhibitor. The present study examined the UA-lowering and prognostic effects of febuxostat in patients with HF compared with conventional allopurinol.

Methods

This multicenter, randomized trial included 263 patients with chronic HF who were randomly assigned to two groups and received allopurinol or febuxostat (UA >7.0 mg/dL). All patients were followed up for 3 years after enrollment.

Results

There were no significant differences in baseline clinical characteristics between the two groups. The UA level was significantly decreased after 3 years of drug administration compared with the baseline in both groups. Urine levels of the oxidative stress marker 8-hydroxy-2′-deoxyguanosine were lower in the febuxostat group than in the allopurinol group (11.0 ± 9.6 vs. 22.9 ± 15.9 ng/mL), and the rate of patients free from hospitalization due to worsening HF tended to be higher in the febuxostat group than in the allopurinol group (89.0% vs. 83.0%).

Conclusions

Febuxostat is potentially more effective than allopurinol for treating patients with chronic HF and hyperuricemia.

This study was registered in the University Hospital Medical Information Network Clinical Trials Registry (https://www.umin.ac.jp/ctr/; ID: 000009817).

Inflammation in Human Heart Failure: Major Mediators and Therapeutic Targets

Inflammation has been recognized as a major pathophysiological contributor to the entire spectrum of human heart failure (HF), including HF with reduced ejection fraction, HF with preserved ejection fraction, acute HF and cardiogenic shock. Nevertheless, the results of several trials attempting anti-inflammatory strategies in HF patients have not been consistent or motivating and the clinical implementation of anti-inflammatory treatments for HF still requires larger and longer trials, as well as novel and/or more specific drugs. The present work reviews the different inflammatory mechanisms contributing to each type of HF, the major inflammatory mediators involved, namely tumor necrosis factor alpha, the interleukins 1, 6, 8, 10, 18, and 33, C-reactive protein and the enzymes myeloperoxidase and inducible nitric oxide synthase, and their effects on heart function. Furthermore, several trials targeting these mediators or involving other anti-inflammatory treatments in human HF are also described and analyzed. Future therapeutic advances will likely involve tailored anti-inflammatory treatments according to the patient's inflammatory profile, as well as the development of resolution pharmacology aimed at stimulating resolution of inflammation pathways in HF.

Serum Sulfhydryl Groups, Malondialdehyde, Uric Acid, and Bilirubin as Predictors of Adverse Outcome in Heart Failure Patients due to Ischemic or Nonischemic Cardiomyopathy

Oxidative stress plays a significant role in the pathogenesis of heart failure (HF). The aim of the study was to investigate the prognostic value of oxidation-reduction (redox) markers in patients with HF due to ischemic and nonischemic cardiomyopathy. The study included 707 patients of HF allocated into two groups depending on ethology: ischemic cardiomyopathy (ICM) (n = 435) and nonischemic cardiomyopathy (nICM) (n = 272), who were followed up for one year. The endpoint occurrence (mortality or heart transplantation) in a 1-year follow-up was similar in the ICM and nICM group. The predictive value of endpoint occurrence of oxidative stress biomarkers such as the serum protein sulfhydryl groups (PSH), malondialdehyde (MDA), uric acid (UA), bilirubin, and MDA/PSH ratio and other clinical and laboratory data were assessed in both groups (ICM and nICM) separately using univariate and multivariate Cox regression analyses. In multivariate analysis, the higher concentrations of UA (p = 0.015, HR = 1.024, 95% CI (1.005-1.044)) and MDA (p = 0.004, HR = 2.202, 95% CI (1.296-3.741)) were significantly associated with adverse prognosis in patients with ICM. Contrastingly, in patients with nICM, we observed that higher bilirubin concentration (p = 0.026, HR = 1.034, 95% CI (1.004-1.064)) and MDA/PSH ratio (p = 0.034, HR = 3.360, 95% CI (1.096-10.302)) were significantly associated with increased risk of death or HT. The results showed the association of different oxidative biomarkers on the unfavorable course of heart failure depending on etiology.

Sacubitril/valsartan: from the PARADIGM-HF trial results to heart failure patients in internal medicine. A narrative review

Data regarding the treatment of heart failure (HF) patients derived from randomized, controlled clinical trials, which, with rare exceptions, appear to be distant from the real world of internal medicine. Many trials have been conducted in cardiology departments: however, the characteristics of patients admitted to cardiology wards are largely different from those of patients hospitalized in internal medicine wards. Recently, the PARADIGM-HF study established the efficacy of sacubitril-valsartan – the first drug of the angiotensin II receptor neprilysin inhibitor (ARNI) class - versus enalapril in increasing survival and reducing hospitalizations in a selected population of HF patients with reduced ventricular function. Although practical guidance on the use of ARNI has been published, it is not specific to HF patients admitted to internal medicine wards. In this review, we examine all available data in order to understand if the characteristics of HF patients followed in internal medicine departments hinder or contraindicate the use of sacubitril-valsartan and what indications appear more appropriate in this setting.

Xanthine oxidoreductase-mediated injury is amplified by upregulated AMP deaminase in type 2 diabetic rat hearts under the condition of pressure overload

BACKGROUND

We previously reported that upregulated AMP deaminase (AMPD) contributes to diastolic ventricular dysfunction via depletion of the adenine nucleotide pool in a rat model of type 2 diabetes (T2DM), Otsuka Long-Evans-Tokushima Fatty rats (OLETF). Meanwhile, AMPD promotes the formation of substrates of xanthine oxidoreductase (XOR), which produces ROS as a byproduct. Here, we tested the hypothesis that a functional link between upregulated AMPD and XOR is involved in ventricular dysfunction in T2DM rats.

METHODS AND RESULTS

Pressure-volume loop analysis revealed that pressure overloading by phenylephrine infusion induced severer left ventricular diastolic dysfunction (tau: 14.7 ± 0.8 vs 12.5 ± 0.7 msec, left ventricular end-diastolic pressure: 18.3 ± 1.5 vs 12.2 ± 1.3 mmHg, p < 0.05) and ventricular-arterial uncoupling in OLETF than in LETO, non-diabetic rats, though the baseline parameters were comparable in the two groups. While the pressure overload did not affect AMPD activity, it increased XOR activity both in OLETF and LETO, with OLETF showing significantly higher XOR activity than that in LETO (347.2 ± 17.9 vs 243.2 ± 6.1 μg/min/mg). Under the condition of pressure overload, myocardial ATP level was lower, and levels of xanthine and uric acid were higher in OLETF than in LETO. Addition of exogenous inosine, a product of AMP deamination, to the heart homogenates augmented XOR activity. OLETF showed 68% higher tissue ROS levels and 47% reduction in mitochondrial state 3 respiration compared with those in LETO. Overexpression of AMPD3 in H9c2 cells elevated levels of hypoxanthine and ROS and reduced the level of ATP. Inhibition of XOR suppressed the production of tissue ROS and mitochondrial dysfunction and improved ventricular function under the condition of pressure overload in OLETF.

CONCLUSIONS

The results suggest that increases in the activity of XOR and the formation of XOR substrates by upregulated AMPD contribute to ROS-mediated diastolic ventricular dysfunction at the time of increased cardiac workload in diabetic hearts.

Machine-learning facilitates selection of a novel diagnostic panel of metabolites for the detection of heart failure

The metabolic derangement is common in heart failure with reduced ejection fraction (HFrEF). The aim of the study was to check feasibility of the combined approach of untargeted metabolomics and machine learning to create a simple and potentially clinically useful diagnostic panel for HFrEF. The study included 67 chronic HFrEF patients (left ventricular ejection fraction-LVEF 24.3 ± 5.9%) and 39 controls without the disease. Fasting serum samples were fingerprinted by liquid chromatography-mass spectrometry. Feature selection based on random-forest models fitted to resampled data and followed by linear modelling, resulted in selection of eight metabolites (uric acid, two isomers of LPC 18:2, LPC 20:1, deoxycholic acid, docosahexaenoic acid and one unknown metabolite), demonstrating their predictive value in HFrEF. The accuracy of a model based on metabolites panel was comparable to BNP (0.85 vs 0.82), as verified on the test set. Selected metabolites correlated with clinical, echocardiographic and functional parameters. The combination of two innovative tools (metabolomics and machine-learning methods), both unrestrained by the gaps in the current knowledge, enables identification of a novel diagnostic panel. Its diagnostic value seems to be comparable to BNP. Large scale, multi-center studies using validated targeted methods are crucial to confirm clinical utility of proposed markers.

Malondialdehyde and Uric Acid as Predictors of Adverse Outcome in Patients with Chronic Heart Failure

In chronic heart failure (HF), some parameters of oxidative stress are correlated with disease severity. The aim of this study was to evaluate the importance of oxidative stress biomarkers in prognostic risk stratification (death and combined endpoint: heart transplantation or death). In 774 patients, aged 48-59 years, with chronic HF with reduced ejection fraction (median: 24.0 (20-29)%), parameters such as total antioxidant capacity, total oxidant status, oxidative stress index, and concentration of uric acid (UA), bilirubin, protein sulfhydryl groups (PSH), and malondialdehyde (MDA) were measured. The parameters were assessed as predictive biomarkers of mortality and combined endpoint in a 1-year follow-up. The multivariate Cox regression analysis was adjusted for other important clinical and laboratory prognostic markers. Among all the oxidative stress markers examined in multivariate analysis, only MDA and UA were found to be independent predictors of death and combined endpoint. Higher serum MDA concentration increased the risk of death by 103.0% (HR = 2.103; 95% CI (1.330-3.325)) and of combined endpoint occurrence by 100% (HR = 2.000; 95% CI (1.366-2.928)) per μmol/L. Baseline levels of MDA in the 4^th quartile were associated with an increased risk of death with a relative risk (RR) of 3.64 (95% CI (1.917 to 6.926), p < 0.001) and RR of 2.71 (95% CI (1.551 to 4.739), p < 0.001) for the occurrence of combined endpoint as compared to levels of MDA in the 1^st quartile. Higher serum UA concentration increased the risk of death by 2.1% (HR = 1.021; 95% CI (1.005-1.038), p < 0.001) and increased combined endpoint occurrence by 1.4% (HR = 1.014; 95% CI (1.005-1.028), p < 0.001), for every 10 μmol/L. Baseline levels of UA in the 4^th quartile were associated with an increased risk for death with a RR of 3.21 (95% CI (1.734 to 5.931)) and RR of 2.73 (95% CI (1.560 to 4.766)) for the occurrence of combined endpoint as compared to the levels of UA in the 1^st quartile. In patients with chronic HF, increased MDA and UA concentrations were independently related to poor prognosis in a 1-year follow-up.

Uric acid: from a biological advantage to a potential danger. A focus on cardiovascular effects

Non-communicable diseases represent nowadays the most common cause of death worldwide, having largely overcome infectious diseases. Among them, cardiovascular diseases constitute the majority. Given these premise, great efforts have been made by scientific societies to emphasize the fundamental role of cardiovascular prevention and risk factors control. In addition to classical cardiovascular risk factors such as smoking, arterial hypertension, hypercholesterolemia and male gender, new risk factors are emerging from international literature. Among them, uric acid is the protagonist. Several evidences show a direct role of hyperuricemia in the determinism of metabolic and vascular disorders. From the other hand, some researchers have demonstrated that uric acid is only a marker of cardiovascular damage and not a risk factor for its development. Aim of this review is to evaluate the scientific evidences on the role of uric acid in cardiovascular diseases in order to shed light on this confusing topic.

Predictors of cardiovascular outcome and rehospitalization in elderly patients with heart failure

BACKGROUND

Heart failure (HF) is a major public health problem and represents the only cardiac disease continuing to increase in prevalence, in particular among elderly patients. The frequent rehospitalizations have a negative impact on quality of life of patients with HF, constituting a substantial cost for patients and the health system. The aim of this review was to look into biochemical, echocardiographic and socioeconomical parameters as predictors of clinical outcomes and rehospitalizations.

METHODS

This narrative review is based on the material searched for and obtained via PubMed from January 2000 up to March 2018. The search terms we used were as follows: "elderly, heart failure, cardiovascular" in combination with "biomarker, echocardiography and hospitalization."

RESULTS

This review analyses the potential predictive role of biochemical and echocardiographic and socioeconomical parameters on clinical outcomes (particularly cardiovascular) and hospital readmissions in patients with chronic HF. We focused on risk stratification of elderly patients with HF, who constitute a category of frail subjects at higher risk for readmission to hospital.

CONCLUSIONS

In elderly subjects with chronic HF, the risk stratification could benefit of a multiparametric approach combining biochemical, echocardiographic, demographic and socioeconomical parameters, thus ensuring a better quality of life and at the same time a better allocation of financial resources.

Gender differences in association between uric acid and all-cause mortality in patients with chronic heart failure

Background

Elevated serum uric acid (SUA) is associated with poor prognosis in patients with cardiovascular disease, yet it is still not decided whether the role of SUA is causal or only reflects an underlying disease. The purpose of the study was to investigate if SUA was an independent predictor of 5-year all-cause mortality in a propensity score matched cohort of chronic heart failure (HF) outpatients. Furthermore, to assess whether gender or renal function modified the effect of SUA.

Methods

Patients (n = 4684) from the Norwegian Heart Failure Registry with baseline SUA were included in the study. Individuals in the highest gender-specific SUA quartile were propensity score matched 1:1 with patients in the lowest three SUA quartiles. The propensity score matching procedure created 928 pairs of patients (73.4% males, mean age 71.4 ± 11.5 years) with comparable baseline characteristics. Kaplan Meier and Cox regression analyses were used to investigate the independent effect of SUA on all-cause mortality.

Results

SUA in the highest quartile was an independent predictor of all-cause mortality in HF outpatients (hazard ratio (HR) 1.19, 95% confidence interval (CI) 1.03–1.37, p-value 0.021). Gender was found to interact the relationship between SUA and all-cause mortality (p-value for interaction 0.007). High SUA was an independent predictor of all-cause mortality in women (HR 1.65, 95% CI 1.24–2.20, p-value 0.001), but not in men (HR 1.06, 95% CI 0.89–1.25, p-value 0.527). Renal function did not influence the relationship between SUA and all-cause mortality (p-value for interaction 0.539).

Conclusions

High SUA was independently associated with inferior 5-year survival in Norwegian HF outpatients. The finding was modified by gender and high SUA was only an independent predictor of 5-year all-cause mortality in women, not in men.

Elevated serum uric acid concentration at discharge confers additive prognostic value in elderly patients with acute heart failure

BACKGROUND AND AIMS

Elevated serum uric acid (sUA) concentrations have been associated with worse prognosis in heart failure (HF) but little is known about elderly patients. We aimed to assess long-term additive prognostic value of sUA in elderly patients hospitalized for HF.

METHODS AND RESULTS

Clinical and echocardiographic characteristics of 310 consecutive elderly patients hospitalized for HF were collected. During index period, 206 had sUA concentrations available, which were obtained within 24 h prior to discharge; 10 patients were lost to follow-up, leaving 196 patients available. Patients had a median age of 77 (IQR 69-83) years, and were mostly male (64.5%). sUA ranges for tertiles I-III were: 1.5-6.1, 6.2-8.3, and 8.4-18.9 mg/dl, respectively. During a median follow-up of 27 months (IQR 10.5-39.5), 122 combined events occurred (87 deaths and 73 HF rehospitalizations). Four-year event-free survival for the combined endpoint was 46 ± 7% for tertile I, 34 ± 7% for tertile II, and 21 ± 5% for tertile III (P = 0.001). By multivariable Cox backward analysis, sUA was retained as a significant predictor. Compared with the lowest sUA tertile, tertile III showed a strong association with outcome, also after adjustment for other predictors (HR 1.84, 95% CI 1.16-2.93; P = 0.01). Importantly, addition of sUA to the other significant predictors of outcome resulted in improved risk classification (net reclassification improvement 0.19, P = 0.017).

CONCLUSIONS

High sUA at discharge is a strong predictor of adverse outcome in elderly hospitalized for HF, and it significantly improves risk classification. Measuring sUA can be a simple and useful tool to identify high-risk elderly hospitalized for HF.

Red cell distribution width and uric acid in patients with obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA), characterized by recurrent partial or complete pharyngeal closure, resulting in apnea or hypopnea, is closely associated with cardiovascular disorders (CVDs). Elevated red cell distribution width (RDW) and serum uric acid (SUA) levels have also been associated with CVDs and the consequent mortality. The aim of this study is to determine SUA levels and RDW in patients with OSA which is major a risk factor for CVDs.

METHODS

This was a retrospective study involving 600 subjects evaluated by polysomnography. Patients were grouped according to the apnea-hypopnea index (AHI), expressed as control group or as mild OSA, moderate OSA, and severe OSA groups.

RESULTS

The mean RDW and the mean SUA were significantly higher in the severe OSA group than in all other groups (P < .015 and P < .003, respectively, for all). RDW was negatively correlated with minimum S_pO2 (r = -.142, P < .01) and positively correlated with mean oxygen desaturation time (r = .113, P < .05). SUA was negatively correlated with minimum S_pO2 (r = -.229, P < .01). The RDW was significantly higher in the OSA patients with CVDs than in those with OSA only (P < .05), although there was no significant difference between the OSA patients with and without CVDs in terms of the SUA in any of the groups (P > .05).

CONCLUSIONS

Elevated levels of SUA and RDW were associated with OSA severity, as defined by AHI. In addition, RDW was significantly higher in severe OSA with CVDs.

Serum Uric Acid level in the severity of Congestive Heart Failure (CHF)

BACKGROUND AND OBJECTIVE

It has been observed that in a clinical condition like hypoxemia there is an increase in the serum Uric acid level. The objective of our study was to find out the relationship between serum uric acid levels in the severity of Heart failure.

METHODS

We analyze 285 patients with a diagnosis of Congestive heart failure admitted in Lady Reading Hospital Peshawar from March 1st to August 2016. Age group of patients was 17- 67 years. New York Health Association (NYHA) scoring were used to access the severity of Congestive Heart Failure. Serum UA level >7.0 mg/dl was considered high.

RESULTS

Total 285 patients with CHF were analyzed with a mean age of 54±2.8 years in which males were 65.96% and 34.03% were female. 40% were in class II of New York Health Association (NYHA), 32.63% in class III and 25.61% in class IV and 1.75% were in class I. Out of 285, 59.29% met the definition of hyperuricemia. In which 83.43% were male and 16.57% were female. Most of the Hyperuricemic patients 62.13% were in age group of 51- 60 years, with a mean age of 57±4.5 years. We found a significant correlation between uric acid level and BNP (p= <0.001), and use of diuretics (p=<0.001). 34.93% of the Hyperuricemic CHF patients were in NYHA III and NYHA IV whose SUA was above 8 mg/dl as compared to 31.57% Hyperuricemic CHF patients whose SUA was below 8 mg/dl.

CONCLUSION

High serum Uric acid was observed in 59.29% of patients with CHF. The observed significant correlation between UA level and some established prognostic markers in these patients may indicate that serum UA could provide additional prognostic information in this population. SUA as a marker can be measured anywhere at a low cost to help identify high-risk patients with CHF. Lowing uric acid is expected to be a new approach for prevention and therapy of HF.

Prognostic Significance of Hyperuricemia in Patients With Acute Heart Failure

Serum uric acid (UA) is associated with death and hospitalization in chronic heart failure (HF). However, UA in acute HF has not been well studied with respect to its relation to renal dysfunction and vascular congestion. We measured admission serum UA along with baseline variables in 281 patients with acute HF screened from the Loop Diuretics Administration and Acute Heart Failure (Diur-HF) trial. Hyperuricemia was defined as serum UA >7 mg/dl in men and >6 mg/dl in women. Chronic kidney disease (CKD) was defined as an estimated glomerular filtration rate <60 ml/min/1.73 m(2) before hospital admission. Death or HF hospitalization at 6 months was the primary outcome. The mean UA concentration was 6.4 ± 2.5 mg/dl, and 121 patients (43.1%) were classified as hyperuricemic. UA values were significantly increased in patients with CKD compared to patients without CKD (6.8 ± 2.7 vs 6.1 ± 2.1 mg/dl; p = 0.02); however, UA was not associated with the development of acute kidney injury. Patients with hyperuricemia had greater degrees of pulmonary and systemic congestion than normouricemic patients (congestion score 3.5 vs 2.1, p <0.01). Hyperuricemia was associated with higher risk of death or HF rehospitalization (univariate hazard ratio 1.46 [1.02 to 2.10]; p = 0.04, multivariate hazard ratio 1.69 [1.16 to 2.45]; p = 0.005). In conclusion, hospitalized patients with acute HF, elevated UA levels were associated with both CKD and pulmonary congestion. After controlling for potential confounders, hyperuricemia was associated with rehospitalization and death at 6 months.

Uric acid and xanthine oxidase in heart failure - Emerging data and therapeutic implications

The role of hyperuricaemia as cardiovascular risk factor has exhaustingly been debated for decades. While the association of elevated uric acid (UA) levels with increased mortality risk as convincingly been shown, the question whether UA is independently predictive of just a related effect within a more complex risk factor profile (including metabolic, inflammatory and haemodynamic risk factors) is still a matter of dispute. In heart failure the independent prognostic and functional impact of elevated UA has not only been shown but also the pathophysiologic mechanism(s) and the potential of targeted therapeutic interventions have been investigated in some detail. The emerging picture suggests the increased activity of the enzyme xanthine oxidase (XO) with corresponding increased production of free oxygen radical (ROS) as a main underlying principle with the resulting increase in UA levels being mostly a marker of this up-regulated pathway. While this concept will not diminish the value of UA as a prognostic marker, it provides the basis for a novel metabolic treatment option and the means to identify those patients most eligible for this tailored therapy. This review will summarize the recent evidence on XO as a novel and promising therapeutic target in heart failure.

Serum uric acid is associated with cardiac diastolic dysfunction among women with preserved ejection fraction

Serum uric acid (SUA) is associated with the severity and prognosis of systolic heart failure. We investigated the potential association between SUA and cardiac diastolic dysfunction among total of 744 cardiac patients (202 women and 542 men) who had preserved left ventricular ejection fraction. Presence of diastolic dysfunction was assessed by echocardiographic data, plasma B-type natriuretic peptide concentration, and left ventricular hypertrophy. Univariate analysis showed that the prevalence of diastolic dysfunction increased with increasing SUA value in women, but not in men. When sex-nonspecific SUA quartiles were used, multivariate logistic regression analysis, among female patients who were not taking uric acid lowering medication, showed that the third (SUA, 5.7-6.4 mg) and the fourth (SUA, ≥6.5 mg/dl) SUA quartiles were associated with diastolic dysfunction with an odds ratio of 3.25 (P < 0.05) and 8.06 (P < 0.001), respectively, when compared with the first SUA quartile (≤4.7 mg/dl). When sex-specific SUA quartiles were used among these population, multivariate logistic regression analysis showed that the fourth SUA quartile (≥5.7 mg/dl) was associated with diastolic dysfunction with an odds ratio of 5.34 (P < 0.05) when compared with the first SUA quartile (≤4.1 mg/dl). By contrast, the relationship between SUA and diastolic dysfunction was not significant in men, irrespective of which of the sex-nonspecific or sex-specific SUA quartiles were used. These data indicated that among cardiac patients with preserved ejection fraction, SUA was significantly associated with diastolic dysfunction in women but not in men.

Uric acid and risk of heart failure: a systematic review and meta-analysis

AIMS

We aimed to perform a systematic review and meta-analysis to assess the association between serum uric acid and incident heart failure (HF)/prognosis of HF patients.

METHODS AND RESULTS

A systematic electronic literature search was conducted in Embase (Ovid SP, from 1974 to May 2013), Medline (Ovid SP, from 1946 to May 2013), and the Chinese Biomedical Literature Database (CBM, from 1978 to May 2013) to identify studies reporting on the association between serum uric acid and HF. Either a random effects model or a fixed effects model was used for pooling data. Five studies reporting on incident HF and 28 studies reporting on the adverse outcomes of HF patients were included. The results showed that hyperuricaemia was associated with an increased risk of incident HF [hazard ratio (HR) 1.65, 95% confidence interval (CI) 1.41-1.94], and the risk of all-cause mortality (HR 2.15, 95% CI 1.64-2.83), cardiovascular mortality (HR 1.45, 95% CI 1.18-1.78), and the composite of death or cardiac events (HR 1.39, 95% CI 1.18-1.63) in HF patients. For every 1 mg/dL increase in serum uric acid, the odds of development of HF increased by 19% (HR 1.19, 95% CI 1.17-1.21), and the risk of all-cause mortality and the composite endpoint in HF patients increased by 4% (HR 1.04, 95% CI 1.02-1.06) and 28% (HR 1.28, 95% CI 0.97-1.70), respectively. Subgroup analyses supported the positive association between serum uric acid and HF.

CONCLUSIONS

Elevated serum uric acid is associated with an increased risk of incident HF and adverse outcomes in HF patients.

Uric acid in heart failure: a biomarker or therapeutic target?

There is a need for a cost-effective prognostic biomarker in heart failure (HF). Substantial evidence suggests that uric acid (UA) is an independent marker for adverse prognosis in acute and chronic HF of varying severity. Whether UA is a merely a marker of poor prognosis or is an active participant in disease pathogenesis is currently unknown. In the setting of HF, at least two different processes can be responsible for increased UA: increased production, which may result from oxidative stress, and decreased excretion due to renal insufficiency, which can be a consequence of cardio-renal syndrome, renal congestion, or comorbidities. While pioneer studies have raised the possibility of preventing HF through the use of UA lowering agents, namely xanthine oxidase inhibitors and uricosurics, the literature is still conflicting on whether the reduction in UA will result in a measurable clinical benefit. In this review, we examine the evidence relating UA to HF prognosis, the mechanisms that contribute to increased UA levels in HF, and future novel treatments aimed at reducing UA levels.

Association between uric acid levels and obstructive sleep apnea syndrome in a large epidemiological sample

INTRODUCTION

Recurrent hypoxia, which is associated with obstructive sleep apnea syndrome (OSAS), leads to an increase in the degradation of adenosine triphosphatase into xanthine, which in turn increases uric acid concentrations.

OBJECTIVE

The current study aimed to determine whether an association exists between OSAS and uric acid levels in the peripheral blood from a representative population of Sao Paulo (Brazil).

METHODS

A population-based survey adopting a probabilistic 3-stage cluster sample of Sao Paulo was used to represent the population according to gender, age, and socioeconomic class. A total of 1,042 volunteers underwent polysomnography recordings for OSAS diagnosis, blood pressure assessment, and biochemical blood analysis, and answered questionnaires.

RESULTS

Uric acid levels were correlated with most important risk factors for OSAS, such as AHI, desaturation time and index, minimum oxyhemoglobin saturation (SpO2), blood pressure, cholesterol, BMI, triglycerides and arousal, and with OSAS itself. Also, uric acid was increased in OSAS volunteers even after controlling for all confounders. Hyperuricemic volunteers presented lower mean and minimum SpO2 and increased desaturation index. Importantly, minimum SpO2 was a significant predictor of uric acid levels, which in turn was considered an independent predictor for OSAS in the binary logistic model. However, a ROC curve analysis for establishing cut-off points for uric acid levels as a biomarker of OSAS revealed moderate sensitivity and specificity.

CONCLUSION

A strong association was found between uric acid levels and OSAS in a representative sample of the population of Sao Paulo. Although they do not qualify for a biomarker alone, uric acid levels may be involved in OSAS severity and should be considered in sleep apnea management in the future.

Uric acid, allopurinol therapy, and mortality in patients with acute heart failure--results of the Acute HEart FAilure Database registry

STUDY OBJECTIVE

The aim of this study was to explore the prognostic role of serum uric acid (UA) measurement in the hospital and long-term mortality assessment in subjects with acute heart failure (AHF) from the Acute HEart FAilure Database registry (AHEAD). The AHEAD registry comprised 4153 patients with AHF syndromes hospitalized at the AHEAD participating centers.

PATIENTS AND METHODS

The study included 1255 patients who were admitted to the AHEAD participating centers with acute decompensated chronic heart failure, de novo heart failure, or cardiogenic shock between September 2006 and October 2009 and who had information about serum UA concentration available at the time of hospital admission. The hospital and long-term mortality was followed using the centralized database of the Ministry of Health, Czech Republic. The mean age of the cohort was 73.4 years, the female population represented 43%, the median hospital stay was 8 days, and the mean hospital mortality was 7.6%.

RESULTS

The median UA concentration of the patients with AHF was 432 μmol/L (7.26 mg/dL), the median estimated glomerular filtration rate (eGFR) was 49.0 mL/min, and N-terminal pro-brain natriuretic peptide level was 5510 pg/mL. Among other laboratory variables, UA concentration greater than 515 μmol/L (8.67 mg/dL) was associated with increased hospital mortality (P < .001), as well as eGFR less than 30 mL/min (P < .001), Na 135 mmol/L or less, and positive troponin. Uric acid concentration greater than 500 μmol/L (8.41 mg/dL) was associated with increased long-term mortality (P < .001), followed by eGFR less than 30 mL/min (P < .001), Na 135 mmol/L or less, and hemoglobin level lower than 130 g/L (P < .001). The 1-year survival rate of patients discharged from hospital (n = 1159) was 75.6%, and the 2-year rate was 66.8%. Survival of patients treated with allopurinol for hyperuricemia was significantly lower compared with untreated subjects (70.1 vs 77.2 for 1-year survival and 60.3 vs 68.5 for 2-year survival).

CONCLUSION

In patients with AHF, increased UA levels and documented allopurinol therapy for hyperuricemia were associated with increased hospital and long-term mortality. Allopurinol therapy is not a cause but the identifier of the subjects at risk.

Xanthine oxidase and uric acid in cardiovascular disease: clinical impact and therapeutic options

The association between increased uric acid (UA) levels and cardiovascular disease (CVD) has been observed and studied for many decades. The value of UA as an independent factor within the metabolic risk profile for prediction of CVD in the normal population remains an issue of ongoing discussion. In turn, increasing evidence suggests that among patients with established CVD such as heart failure UA is an independent marker of disease state and prognosis. Increased UA levels may be an indicator of up-regulated activity of xanthine oxidase, a powerful oxygen radical-generating system in human physiology. Increased reactive oxygen species (ROS) accumulation contributes to endothelial dysfunction, metabolic and functional impairment, inflammatory activation, and other features of cardiovascular pathophysiology. Accordingly, inhibition of xanthine oxidase activity has been shown to improve a range of surrogate markers in patients with CVD, but this effect seems to be confined to hyperuricemic patients because disappointing results were reported in studies with normouricemic patients. In this review we summarize current evidence on hyperuricemia in CVD. The value of UA as a biomarker and as a potential therapeutic target for tailored metabolic treatment in CVD is discussed.

Allopurinol as a cardiovascular drug

Cardiovascular disease (CVD) remains the leading cause of death in the United States. There is evidence that shows a direct relationship between an elevated uric acid level and an increased risk of cardiovascular (CV) events, which has set the foundation for the investigation of uric acid-lowering drugs for the treatment of CVD. Although traditionally the cornerstone therapy for gout, allopurinol's ability to be a competitive inhibitor of the key enzyme, xanthine oxidase, needed for uric acid formation, has prompted recent clinical research evaluating allopurinol as a CV drug. Epidemiologic and biochemical studies on uric acid formation have shown that it is not only uric acid itself that leads to worsening prognosis and increased CV events, but also the free radicals and superoxides formed during xanthine oxidase activity. The combination of uric acid formation and formed free radicals could ultimately lead to coronary endothelial dysfunction and worsening of myocardial oxidative stress. Along with preventing uric acid formation, allopurinol also has the ability to behave as a free radical scavenger of the superoxide anions and free radicals released during uric acid formation.Clinical studies have shown that allopurinol improves endothelial dysfunction and subsequently improves the exercise capacity in patients diagnosed with angina pectoris. Allopurinol has also been shown to decrease oxidative stress and ameliorate the morbidity and mortality of congestive heart failure patients by possibly improving mechanoenergetic uncoupling, with the enhancement of myocardial contractility and the left ventricular ejection fraction. This review presents the pharmacologic action of allopurinol on the CV system and describes the effectiveness of allopurinol as a potential drug to treat 2 CVD morbidities: ischemic heart disease and congestive heart failure.

Uric acid, heart failure survival, and the impact of xanthine oxidase inhibition

Increasing evidence suggests that serum uric acid (UA), a product of xanthine oxidase (XO), may be a useful marker for metabolic, hemodynamic, and functional staging in heart failure (HF) and a valid predictor of survival in HF patients. Recent data support an expanded role for UA and the XO pathway in the pathogenesis of HF, as studies have shown that an elevation in the enzymatic activity of XO can lead to increases in oxidative stress, endothelial dysfunction, and reduced myocardial function. Numerous population studies have previously reported that elevated UA levels are an independent predictor of cardiovascular mortality, and recent evidence suggests that lowering serum levels of UA may lead to improved outcomes in HF patients. The question of whether UA is only a marker rather than a causal factor in the pathogenesis of HF remains. Regardless of whether UA levels are ready for routine clinical use, either as a prognostic factor or novel therapeutic target, further prospective studies are necessary to demonstrate that routine measurement or reduction of UA levels improves outcomes in HF patients.

Uric acid as a predictor of all-cause mortality in heart failure: a meta-analysis

Serum uric acid (SUA) is a product of xanthine oxidase (XO). Apoptosis and tissue hypoxia lead to increased purine catabolism, which, in turn, increases XO activity and subsequently SUA levels. The purpose of this study was to perform a meta-analysis to evaluate the evidence supporting SUA as a predictor of all-cause mortality in patients with heart failure (HF) and to determine the SUA cut-off for the increase in risk. A search of the MEDLINE database (1966 to March 2009) supplemented by manual searches of bibliographies of key relevant articles was performed. The authors selected all cohort studies in which SUA was measured and mortality was reported in patients with HF. The pooled relative risk (RR) with the corresponding 95% confidence interval (CI) for all-cause mortality using the fixed-effects method was calculated. The effects of SUA on all-cause mortality at different SUA cut-offs using meta-regression was evaluated. The search strategy yielded 358 studies, of which only 6 met our eligibility criteria. The studies, however, comprised 1456 evaluable patients with HF, with a median ejection fraction of 32% (range, 26%-40%). The RR of all-cause mortality was 2.13 (95% CI, 1.78-2.55) for SUA>6.5 mg/dL compared with <6.5 mg/dL SUA level. There was a linear association (P<.01) between SUA and mortality after 7 mg/dL. Uric acid is an important prognostic marker for all-cause mortality in HF. SUA levels >7 mg/dL are associated with higher all-cause mortality.

Serum uric acid levels correlate with filling pressures in systolic heart failure

The authors studied the relationship between liver function tests and serum uric acid level with clinical and hemodynamic profiles in heart failure. Fifty patients (aged 44±15 years; 74.5% men) with an ejection fraction (EF) <35% were enrolled and clinical assessment was performed. Hemodynamic indices (including pulmonary arterial pressure [PAP], pulmonary capillary wedge pressure [PCWP], and cardiac index were studied by standard Edwards Lifesciences Swan-Ganz catheters, and liver function tests and serum uric acid level were measured simultaneously. Fifty age- and sex-matched controls with normal EF were also studied. A total of 73% of patients had ischemic cardiomyopathy. Mean uric acid level was 7.2±3.8 mg/dL and was significantly higher than in the control group (P value<.001). In multivariate analysis, uric acid correlated significantly with PAP (r=.5, P<.001) and PCWP (r=.4, P=.002) and was also associated with clinical signs of rales, edema, paroxysmal nocturnal dyspnea (r=.5, P=.01), and New York Heart Association class (r=.4, P=.005). Uric acid level was also correlated inversely with left ventricular EF (r=.27, P=.006). Elevated uric acid levels in patients with systolic heart failure is associated with impaired clinical and hemodynamic profile and might be used as a noninvasive indicator of elevated left ventricular filling pressures.

Hyperuricaemia, chronic kidney disease, and outcomes in heart failure: potential mechanistic insights from epidemiological data

AIM

To determine if the association between hyperuricaemia and poor outcomes in heart failure (HF) varies by chronic kidney disease (CKD).

METHODS AND RESULTS

Of the 2645 systolic HF patients in the Beta-Blocker Evaluation of Survival Trial with data on baseline serum uric acid, 1422 had hyperuricaemia (uric acid ≥6 mg/dL for women and ≥8 mg/dL for men). Propensity scores for hyperuricaemia, estimated for each patient, were used to assemble a matched cohort of 630 pairs of patients with and without hyperuricaemia who were balanced on 75 baseline characteristics. Associations of hyperuricaemia with outcomes during 25 months of median follow-up were examined in all patients and in those with and without CKD (estimated glomerular filtration rate of <60 mL/min/1.73 m(2)). Hyperuricaemia-associated hazard ratios (HRs) and 95% confidence intervals (CI) for all-cause mortality and HF hospitalization were 1.44 (1.12-1.85, P = 0.005) and 1.27 (1.02-1.58, P = 0.031), respectively. Hazard ratios (95% CIs) for all-cause mortality among those with and without CKD were 0.96 (0.70-1.31, P = 0.792) and 1.40 (1.08-1.82, P = 0.011), respectively (P for interaction, 0.071), and those for HF hospitalization among those with and without CKD were 0.99 (0.74-1.33, P = 0.942) and 1.49 (1.19-1.86, P = 0.001), respectively (P for interaction, 0.033).

CONCLUSION

Hyperuricaemia has a significant association with poor outcomes in HF patients without CKD but not in those with CKD, suggesting that hyperuricaemia may predict poor outcomes when it is primarily a marker of increased xanthine oxidase activity, but not when it is primarily due to impaired renal excretion of uric acid.

Hyperuricemia associated with rapid renal function decline in elderly Taiwanese subjects

BACKGROUND/PURPOSE

Hyperuricemia is encountered frequently in patients with chronic kidney disease (CKD). We tested the hypothesis that uric acid influences glomerular filtration rate (GFR) and is associated with renal function decline in elderly Taiwanese subjects.

METHODS

We enrolled 800 elderly Taiwanese subjects for a health checkup. Estimated GFR (eGFR) was measured using the Modification of Diet in Renal Disease Study equation. eGFR < 60 mL/min/1.73 m2 was used to analyze the prevalence and incidence of CKD. Significant renal function decline was defined as a decrease in eGFR of > or = 3 mL/min/1.73 m2 per year.

RESULTS

The prevalence of CKD was 18.0% in the elderly subjects. Mean serum uric acid level was 6.6 mg/dL in male and 5.6 mg/dL in female subjects, and eGFR was 71.7 mL/min/1.73 m2. Uric acid levels were associated independently and negatively with eGFR after adjusting for conventional factors of renal function decline. One hundred and sixty-two individuals (31.2%) had a significant decline in renal function. As uric acid level increased by 1 mg/dL, the odds of a significant eGFR decline increased by 1.208.

CONCLUSION

Serum uric acid level was associated with eGFR and decline in renal function in elderly Taiwanese subjects. Whether hypouricemic therapy could retard the progression of CKD deserves further in-depth study.

Uric acid-lowering treatment with benzbromarone in patients with heart failure: a double-blind placebo-controlled crossover preliminary study

BACKGROUND

Hyperuricemia is common in chronic heart failure (CHF), and it is a strong independent marker of prognosis. Upregulated xanthine oxidase (XO) activity and impaired renal excretion have been shown to account for increased serum uric acid (UA) levels in CHF. Therapeutic interventions with allopurinol to reduce UA levels by XO inhibition have been shown to be beneficial. Discussions are ongoing whether UA itself is actively involved or it is a mere marker of upregulated XO activity within CHF pathophysiology. Therefore, the aim of this study was to test the effect of lowering UA by uricosuric treatment without XO inhibition on hemodynamic and metabolic characteristics of CHF. Impaired renal excretion of UA was taken into account.

METHODS AND RESULTS

Serum UA (SUA), urinary UA (uUA) excretion, and renal clearance test for UA (Cl(UA)) were measured in 82 patients with CHF. SUA was significantly increased compared with controls of similar age (control, 5.45+/-0.70 mg/dL; New York Heart Association I, 6.48+/-1.70 mg/dL; New York Heart Association II, 7.34+/-1.94 mg/dL; New York Heart Association III, 7.61+/-2.11 mg/dL; P<0.01). Patients with CHF showed lower uUA excretion and Cl(UA). On multivariate analysis, insulin, brain natriuretic peptide (P<0.01), and creatinine levels (P=0.05) showed independent correlation with SUA. The treatment effect of the uricosuric agent benzbromarone was tested in 14 patients with CHF with hyperuricemia in a double-blind, placebo-controlled, randomized crossover study design. Benzbromarone significantly decreased SUA (P<0.01). Brain natriuretic peptide, left ventricular ejection fraction, and dimensions in echocardiographic assessment did not change after benzbromarone therapy. In contrast, fasting insulin (placebo, 18.8+/-8.9 microU/mL; benzbromarone, 11.0+/-6.2 microU/mL; P<0.05), homeostasis model assessment of insulin resistance index (placebo, 5.4+/-2.6; benzbromarone, 3.0+/-1.7; P<0.05), and tumor necrosis factor-alpha (placebo, 2.59+/-0.63 pg/mL; benzbromarone, 2.14+/-0.51 pg/mL; P<0.05) improved after benzbromarone, and the changes in tumor necrosis factor-alpha levels were correlated with reduction of SUA (P<0.05).

CONCLUSIONS

These results show that UA lowering without XO inhibition may not have an effect on hemodynamic impairment in CHF pathophysiology. To the extent that these data are correct, this finding suggests that upregulated XO activity rather than UA itself is actively involved in hemodynamic impairment in CHF. Clinical Trial Registration- clinical trials.gov. Identifier: NCT00422318.

Diagnostic and prognostic value of uric acid in patients with acute dyspnea

BACKGROUND

Uric acid was shown to predict outcome in patients with stable chronic heart failure. Its impact in patients admitted in the Emergency Department with acute dyspnea, however, remains unknown.

METHODS

We prospectively investigated the diagnostic and prognostic value of uric acid in 743 unselected patients presenting to the Emergency Department with acute dyspnea.

RESULTS

Uric acid at admission was higher in patients with acute decompensated heart failure (51% of the cohort) as compared with patients with noncardiac causes of dyspnea (median, 447 micromol/L vs 340 micromol/L, P <.001). The area under the receiver operating characteristic curve for the accuracy to detect acute decompensated heart failure was inferior for uric acid (0.70) than for B-type natriuretic peptide (area under the receiver operating characteristic curve 0.91, P <.001). Patients in the highest uric acid tertile more often required admission to the hospital (92% vs 74% in the first tertile, P <.001) and had higher in-hospital mortality (13% vs 4% in the first tertile, P <.001). Cumulative 24-month mortality rates were 28% in the first, 31% in the second, and 50% in the third tertile (P <.001). After adjustment in multivariable Cox proportional hazard analysis, uric acid predicted 24-month mortality independently of B-type natriuretic peptide (P=.003).

CONCLUSIONS

Our study first shows that uric acid, measured at Emergency Department admission or hospital discharge, is a powerful predictor of long-term outcome in dyspneic patients.

Hyperuricemia in acute heart failure. More than a simple spectator?

BACKGROUND

Hyperuricemia is a prevalent condition in chronic heart failure (CHF), describing increased oxidative stress and inflammation. Although there is evidence that serum uric acid (UA) predicts mortality in CHF, its role as a prognostic biomarker in acute heart failure (AHF) has not yet been well assessed. The aim of this study was to determine if UA levels predict all-cause mortality. Additionally, as a secondary endpoint we sought the clinical predictors of UA serum level in this population.

METHODS

We analyzed 560 consecutive patients with AHF admitted in a single university center. UA (mg/dl) was measured during early hospitalization. Patient survival status was followed up after discharge (median follow-up: 330 days). The independent association of UA level with all-cause mortality was analyzed using Cox regression analysis.

RESULTS

During follow-up 165 (29.5%) deaths were identified. Patients with UA levels above the median value (>or=7.7 mg/dl) exhibited higher mortality rates (21.1 vs. 37.9%; p<0.001). In multivariable analysis, after adjusting for recognized prognostic factors and potential confounders, UA>or=7.7 mg/dl and per change in 1 mg/dl of UA was associated with an increased risk of mortality (HR 1.45, CI 95%=1.03-2.44; p=0.03 and HR 1.08, CI 95%=1.01-1.15; p=0.03, respectively).

CONCLUSION

UA serum levels is an independent predictor of all-cause mortality in an unselected patients admitted with AHF.

Role of xanthine oxidoreductase in cardiac nitroso-redox imbalance

Emerging evidence supports the importance of nitroso-redox balance in the cardiovascular system. Xanthine oxidoreductase (XOR) is a major oxidative enzyme and increased XOR activity, leading to both increased production of reactive oxygen species and uric acid, is implicated in heart failure. Within the heart, XOR activity stimulates cardiomyocyte hypertrophy, apoptosis, and impairs matrix structure. The underpinnings of these derangements can be linked not solely to oxidative stress, but may also involve the process of nitroso-redox imbalance. In this regard, XOR interacts with nitric oxide signaling at numerous levels, including a direct protein-protein interaction with neuronal nitric oxide synthase (NOS1) in the sarcoplasmic reticulum. Deficiency or translocation of NOS1 away from this microdomain leads to increased activity of XOR, which in turn impairs excitation-contraction coupling and myofilament calcium sensitivity. There is a mounting abundance of preclinical data supporting beneficial effects of inhibiting XOR, but translation to the clinic continues to be incomplete. A growing understanding of XOR and its role in nitroso-redox imbalance has great potential to lead to improved pathophysiologic insights and possibly therapeutic advances.

Higher circulating levels of uric acid are prospectively associated with better muscle function in older persons

BACKGROUND

Previous studies have shown that oxidative protein damage is independently associated with low grip strength and that dietary intake and circulating levels of antioxidant vitamins are positive predictors of muscle strength among older persons. Since uric acid (UA), has strong antioxidant properties, we tested the hypothesis that UA levels is cross-sectionaly associated with muscle strength and protective against the decline of strength over the aging process.

SUBJECTS AND METHODS

789 InCHIANTI Study participants underwent baseline serum UA, handgrip and knee extension torque measurements. Of these, 497 participants (226 men and 271 women, mean age 76.0+/-5.4 years) also had follow-up strength measures. Lifestyle, comorbidities, nutritional profile, inflammatory markers and other laboratory measures were considered as potential confounders.

RESULTS

Follow-up strength measures significantly increased across baseline UA tertiles. After adjusting for potential confounders and analogous baseline strength measures, higher baseline UA levels still remained significantly associated with higher follow-up strength measures.

CONCLUSIONS

Our findings suggest that higher levels of UA might represent a protective reaction aimed at counteracting the excessive production of free radicals that cause muscle protein damage and eventually contribute to the decline of muscle mass and strength.

Is uric acid itself a player or a bystander in the pathophysiology of chronic heart failure?

Uric acid (UA) is the end product of purine metabolism in humans. Hyperuricemia is often found in patients with chronic heart failure (CHF). The increase of serum UA level is inversely associated with disease severity, cardiac function and prognosis of CHF. Some researchers found that UA had detrimental impact on the cardiovascular system, including mediating immune response upon cell injury, increasing endotoxin-stimulated tumor necrosis factor-alpha production and hence proinflammatory immune activation, increasing blood pressure, and so on. Other researchers found that UA had important antioxidant properties by scavenging various reactive oxygen species. So far, there is no evidence suggest that UA has detrimental effect on the pathophysiology of CHF. Xanthine oxidase (XO) is an enzyme that produces uric acid during purine metabolism. XO activity is up-regulated in failing heart, and serum UA levels reflect the degree of XO activation in CHF. XO plays an important role in the pathophysiology process of CHF, including myocyte apoptosis, endothelial dysfunction and cardiac mechanoenergetic uncoupling. The therapeutic effect of long-term XO inhibition has been confirmed in animal models and partly in human bodies. We hypothesize that UA itself is not a player but a bystander associated with the activation of XO in the pathophysiology of CHF.