Shahrekord University of Medical Sciences Epidemiology and Health System Journal 2980-7891 12 1 2025 06 07 Thiamine Supplementation and its Impact on Ejection Fraction: A Systematic Review and Meta-analysis of Clinical Trials 27 34 10.34172/ehsj.26253 EN Mohammad Hossein Sharifi https://orcid.org/0000-0002-9927-5922 Maryam Jalali https://orcid.org/0000-0003-3319-2048 Sorour Sarihi https://orcid.org/0000-0003-3707-1075 Parisa Keshani https://orcid.org/0000-0002-6309-7175 Firoozeh Abtahi https://orcid.org/0000-0002-8202-465X Samane Nematolahi https://orcid.org/0000-0002-3454-2356 Journal Article 10.34172/ehsj.26253 2024 08 19 2025 04 06 Background and aims: Heart failure (HF) is a serious cardiovascular condition with a high mortality rate. In the last decade, there have been concerns about the use of thiamine as a potential factor for enhancing ejection fraction in people with HF. Accordingly, this study aimed at investigating whether thiamine supplementation affects ejection fraction. Methods: The PubMed, Scopus, and Web of Science databases were systematically searched, and a systematic review and meta-analysis was conducted on the clinical trials performed on thiamine supplementation in patients with HF. Six of the eleven studies included in this systematic review were considered suitable for the meta-analysis (randomized controlled trial and cross-over designs) and 4 within-group designs. The total sample sizes for the systematic review and meta-analysis were 545 and 319. Heterogeneity among the primary studies was assessed using Cochran’s Q test and the I² index. The analyses were conducted with Comprehensive Meta-Analysis software. Eventually, the trim-and-fill method was utilized to verify the validity of the findings. Results: The analysis of the seven eligible studies for meta-analysis (six studies and seven reports) revealed that thiamin had no significant effect on left ventricular ejection fraction (LVEF; P=0.05, 95% CI: -0.003 to 0.46). The results of the subgroup meta-analysis were not significant. Notably, the results of the five within-group comparisons for meta-analysis (four studies and five reports) revealed the considerable effect of thiamin on LVEF (P<0.001, 95% CI: 0.57 to 1.88). Conclusion: Thiamine supplementation might improve ejection fraction in patients with HF. More information on the role of thiamine in HF would help establish a greater degree of accuracy on this matter.