AIM: We aimed to study the effect of COVID-19 on the in-hospital outcomes of percutaneous coronary intervention (PCI) in patients with acute coronary syndrome (ACS). METHOD A systematic literature search was performed in 2nd February 2022 updated in 12(th) December 2022 for recruiting relevant papers. The effect size was computed via the odds ratio (OR) for dichotomous data or standardized
mean difference (SMD) for continuous data along with the 95% confidence interval (95%CI). RESULTS After the screening of 1075 records, we found 11 relevant papers that included 2018 COVID-19 patients and negative controls 21207. ACS patients with COVID-19 had a significant higher mortality rate (OR: 4.95; 95%CI: 3.92-6.36; p <0.01), long hospital stay (days) 19 (SMD: 1.17; 95%CI: 0.92-1.42; p <0.01) and reduced post TIMI 3 score (OR: 0.55; 95%CI: 0.41-0.73; p <0.01) rather than controls. However, we found no significant differences in terms of thrombus aspiration prevalence (OR: 1.88; 95%CI: 0.97-3.65; p =0.06) or door to balloon time (SMD: 0.11; 95%CI: -0.43-0.66; p =0.7). CONCLUSION Despite that we found a significant association between COVID-19 and high mortality, more length of hospital stay and reduced post TIMI 3 score, in ACS patients after PCI, a rigorous analysis of the adjusted hazard ratio -that was absent in all the included studies- by further meta-analysis is recommended to confirm this association. However, close monitoring of COVID-19 in patients with a high risk of developing ACS, is recommended due to the associated hypercoagulability of COVID-19 infection.