Abstract Body (Do not enter title and authors here):

Introduction:
Primary percutaneous coronary intervention (pPCI) is the treatment of choice for patients with ST-segment elevation myocardial infarction (STEMI). Nevertheless, pPCI is still associated with poorer outcomes particularly left ventricular dysfunction. Pressure-controlled intermittent coronary sinus occlusion (PiCSO) is a novel therapeutic approach proposed to improve myocardial perfusion and its function in patients with STEMI. Therefore, we performed this meta-analysis to evaluate the effects of PiCSO on left ventricular function in STEMI patients.

Methods:
We performed a comprehensive search on PubMed, Scopus, and Web of Science. Our primary endpoints were left ventricular ejection fraction (LVEF%), left ventricular end diastolic volume (LVEDV), and left ventricular end systolic volume (LVESV). The secondary endpoint was infarct size. We performed Trial Squential Analysis (TSA), and we pooled our continuous data as mean difference (MD) and 95% confidence interval (CI) in the fixed effects model.

Results:
A total of four studies, with 335 patients, were included in the analysis. Our pooled analysis showed that PiCSO significantly increased LVEF% compared to pPCI (MD = 3.52, 95% CI [1.05, 6.00], P= 0.005). However, there was no significant difference between the two groups in terms of LVESV and LVEDV (MD = -1.1, 95% CI [-9.28, 7.08], P= 0.79; MD = -1.69, 95% CI [-9.14, 5.76], P= 0.66, respectively). With regard to infarct size, a significant reduction was observed in PiCSO group compared to pPCI (MD = -4.26, 95% CI [-7.39, -1.14], P= 0.007). The TSA curve crossed the conventional boundary for statistical significance, indicating that the available evidence reach the predetermined threshold.

Conclusions:
Our meta-analysis revealed that PiCSO could mitigate left ventricular dysfunction in STEMI patients by improving LVEF% and reducing infarct size. Nevertheless, PiCSO failed to show a positive impact on LVESV and LVEDV. Further large-scale studies are warranted to draw a definitive conclusion.