Abstract Body (Do not enter title and authors here): Introduction: Despite recent advances in therapy, chronic ischemic heart failure remains a significant cause of morbidity and mortality worldwide. Stem cell (SC) therapy has recently emerged as a potential therapeutic approach, yet its efficacy remains debatable. We aimed to systematically review and meta-analyze the current evidence to evaluate its effectiveness.

Methods: A comprehensive literature search was conducted across the following databases: PubMed, Embase, and Cochrane, from inspection to April 2024. We identified RCTs with a blinded study design, done on patients diagnosed with chronic ischemic HFrEF, and utilized mesenchymal stem cells as an intervention in comparison to placebo/sham intervention using percutaneous endomyocardial catheter systems. Meta-analysis was conducted using RevMan v5.4 to calculate the odds ratio (OR) at 95% confidence intervals (CI) and a p-value of 0.05. I² was indicated for the assessment of heterogeneity. Sensitivity analysis was done in case of heterogeneity between studies.

Results: A total of twenty studies were included in our meta-analysis. The overall change in left ventricular end-systolic volume (LVESV) and stress SPECT significantly favored the stem cell group (pooled effect size -7.59, 95% CI [-12.28 to -2.89], P=0.002), and (pooled effect size -5.33, 95% CI [-6.73 to -3.93], P=0.00001), respectively. Initially, the change in left ventricular end-diastolic volume (LVEDV) did not favor either group. However, sensitivity analysis which excluded one study at a time, reduced heterogeneity (P=0.01, I²=54%) and showed a significant effect favoring the stem cell group (pooled effect size -3.87, 95% CI [-6.77 to -0.97], P=0.009). However, the overall changes in left ventricular ejection fraction (LVEF) did not favor either of the two groups (pooled effect size 0.08, 95% CI [-0.1 to 0.26], P=0.39). Similarly, the overall change in myocardial oxygen consumption (MVO2) did not favor either group (pooled effect size 0.66, 95% CI [-0.1 to 1.32], P=0.05).

Conclusion: Transendocardial SC therapy demonstrates promising results by significantly improving specific cardiac parameters. While the therapy shows potential, particularly after sensitivity adjustments, its impact on other critical measures like LVEF and MVO2 remains inconclusive. These findings highlight the need for further investigation to fully understand and enhance the therapeutic potential of stem cell interventions in heart failure management.