Background: Routine use of adjunctive devices to percutaneous coronary intervention (PCI) for the treatment of patients of ST-segment elevation myocardial infarction (STEMI) is questionable. Also, the clinical characteristics of STEMI patients that can modulate the treatment benefits of adjunctive devices are not fully understood. Objective: To synthesize the existing literature to summarize the therapeutic benefit of the adjunctive devices and to identify the patient characteristics which relate to this therapeutic benefit. Methods: We conducted (i) meta-analyses of the randomized controlled trials (RCT) comparing the performance of the adjunctive devices with PCI for three reperfusion-related outcomes: myocardial blush grade (MBG) < 3, failed ST-segment resolution (STR), and Thrombolysis In Myocardial Infarction (TIMI) flow grade < 3; (ii) stepwise meta-regressions of the effect of trial characteristics on between-trial heterogeneity; and (iii) analyses to examine whether the reperfusion-related end-points explained the between-trial difference in cardiac death and major adverse cardiac events (MACE). Results: Our meta-analyses represent data from 23 RCT and 5,728 subjects. The overall therapeutic benefit attributable ranged from 32 to 35% for the reperfusion-related outcomes, and thrombectomy devices were more beneficial than the distal protection devices. Meta-regression identified gender, receipt of glycoprotein (GP) IIb/IIIa inhibitor, and baseline TIMI flow grade as significant predictors of improved reperfusion across trials. The available clinical trials were individually underpowered and not designed to detect the influence of adjunctive devices on death or MACE. Conclusions: Routine use of adjunctive devices cannot be recommended. Thrombus burden, treatment with GP IIb/IIIa inhibitors, and gender may modify the reperfusion benefit of adjunctive devices.