Table 1.
Brief summary of studies investigating heart failure (HF) and alterations in microbiota and amino acids.
| References | Sample groups | Methods | Key findings |
|---|---|---|---|
| Sandek et al. (27) | 22 CHF patients and 22 controls | Biopsies of the sigmoid mucosa taken for fluorescence in situ hybridization (FISH) | Mean density of bacteria within mucus was higher in CHF patients; The most frequent strains were Bacteroides/Prevotella in HF patients and controls |
| Sandek et al. (30) | 65 HF patients and 25 controls | Tested by FISH | CHF patients exhibited increased bacteria restricted to the juxtamucosal zone and a lower intestinal blood flow. The mucosal biofilm was altered in HF patients for higher occurrence of strictly anaerobic Eubacterium rectale group and the strictly anaerobic Fusobacterium prausnitzii |
| Pasini et al. (25) | 60 mild CHF patients, 30 moderate to severe CHF patients, and 20 controls | Microbiota in stool samples was measured after 48 h of incubation. Further proof by using bacterial metabolic tests | CHF patients had massive quantities of pathogenic bacteria and Candida, such as Campylobacter, Shigella, Salmonella, Yersinia enterocolitica, and Candida species |
| Luedde et al. (31) | 20 HF patients and 20 controls | 16s rRNA gene sequencing | HF patients had a lower diversity of the gut microbiota. There was a significant decrease in Coriobacteriaceae, Erysipelotrichaceae, and Ruminococcaceae observed on the family level in HFs. On the genus level, Collinsella, uncl. Erysipelotrichaceae, and uncl. Ruminococcaceae showed a significant decrease in HF |
| Kummen et al. (32) | Two cohorts. Discovery: 40 HFs; validation: 44 HFs; 266 controls | 16s rRNA gene sequencing | HF patients had decreased microbial richness and identified changes in 15 taxa, including a depletion of taxa in the Lachnospiraceae family, which are known producers of butyrate |
| Beale et al. (33) | 26 HFpEFs, 39 metropolitan controls and 28 regional controls | 16s rRNA gene sequencing | There was a significant difference in α-diversity and β-diversity between both cohorts of controls and HFpEFs. HFpEFs had a lower Firmicutes-to-Bacteroidetes ratio but not significantly, and depleted bacteria that are short-chain fatty acid producers |
| Cheng et al. (34) | 51 controls and 183 HFs; validation: 63 controls and 218 HFs with stage C | Untargeted metabolic analysis by LC-MS | A panel of metabolites, including histidine, phenylalanine, spermidine, and phosphatidylcholine C34:4, has a diagnostic value similar to B-type natriuretic peptide (BNP). The prognostic value of the metabolite panel, which consisted of the asymmetric methylarginine/arginine ratio, butyrylcarnitine, spermidine, and the total amount of essential amino acids, was better than that of BNP |
| Wang et al. (35) | 94 controls and 599 acute/decompensated HFs; validation: 391 HFs | Plasma was analyzed by UPLC | High-risk type 1 (leucine ≥145 μM and phenylalanine ≥88.9 μM), high-risk type 2 (leucine <81.2 μM) were associated with higher event rates. The prognostic value of types 1 and 2 remained significant after adjusting for age, BNP, and other risk factors in HF |
| Wang et al. (36) | 890 HF outpatients to assess metabolic status, 387 patients to measure metabolic equivalents (MET). | Plasma samples measured by UPLC | HOP (plasma concentrations of histidine, ornithine, and phenylalanine) scores of ≥8.8 stratified patients at higher risk of composite events in a variety of HF populations. In multivariable analysis, HOP scores ≥8.8 remained a powerful event predictor, independent of other risk factors |
| Chen et al. (37) | 115 HFs and 37 controls | Plasma samples measured by UPLC | Phenylalanine ≥112 μM was associated with a lower accumulative survival rate and predicted death over 1 year independently |
| Lu et al. (24) | C57BL/6J mice and male SD rats | Cardiac hypertrophy and HF were induced by TAC surgery or Ang II | Glycine may be a novel cardioprotector against pressure overload-induced cardiac hypertrophy; the protection of glycine might be mediated by glyR α2 through the MAPK (JNK, ERK1/2, and p38) signaling pathways |
| Rozentryt et al. (38) | Placebo group:6; nutrition group:23 | Intervention includes additional 600 kcal per day (proteins 20 g, carbohydrates 72 g, fat 26 g) | The feasibility of oral nutritional supplement in cachectic patients with heart failure and significant clinical benefit in terms of body size and body composition, laboratory parameters, and quality of life |
| Wu et al. (39) | Placebo group:12; active group:14 | Intervention includes a combination of 8 g/day of L-alanyl-L-glutamine and 6.5 g/day of fish oil | The combined supplementation of L-alanyl-L-glutamine and PUFA did not improve exercise performance or muscle function but increased lean body mass and quality-of-life in patients with chronic stable HF |
| Pineda-Juárez et al. (40) | 26 controls and 29 experimental group | Experimental group: the resistance exercise program and received 10 g/day BCAA supplementation, control group: the resistance exercise program. | Improvements in physical and functional capacities are attributed to resistance exercise program but not to the BCAA supplementation |