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.

Aim: This study was designed to systematically evaluate the effects of microbiota-driven therapy on decreasing TMAO and its related metabolites.Methods and Results: PubMed, EMBASE and Cochrane Library databases were searched (up to July 2021). Randomized controlled trials (RCTs), compared microbiota-driven therapy (prebiotics, probiotics, or synbiotics) with placebo on decreasing TMAO and its related metabolites, were eligible. Two researchers extracted the data independently and the disagreement was resolved by a third researcher. The risk of bias of included study was evaluated using Cochrane tool (RoB 2.0). Meta-analysis, meta-regression analysis and publication bias analysis were performed by RevMan 5.3 or Stata 12.0 software. Ten studies (12 arms) involving 342 patients (168 patients in the intervention group and 174 patients in the control group) were included. Compared with the control group, microbiota-driven therapy did not reduce circulating TMAO [SMD = −0.05, 95% CI (−0.36, 0.26), P = 0.749], choline [SMD = −0.34, 95% CI (−1.09, 0.41), P = 0.373], betaine aldehyde [SMD = −0.704, 95% CI (−1.789, 0.382), P = 0.204], and L-carnatine [SMD = −0.06, 95% CI (−0.38, 0.25), P = 0.692].Conclusion: Current evidence does not support that microbiota-driven treatment reduce circulating levels of TMAO, choline, betaine aldehyde, and L-carnitine. However, given the small sample size, this conclusion needs to be proved in the future.Systematic Review Registration: PROSPERO:CRD42019119107.