Alhelaly MM, et al. - A systematic review and meta-analysis were conducted to compare iso-osmolar contrast media (IOCM) and low-osmolar contrast media (LOCM) for vascular attenuation, image quality, heart rate changes, and common patient discomfort symptoms. In this study, PubMed, Web of Science, Scopus, and Cochrane Central Register of Controlled Trials were searched for the database. They enrolled only randomized controlled trials. Three independent authors reviewed screening, data extraction, and quality assessment. For the meta-analysis, they used RevMan 5.3 software. They recruited nine studies involving a sum of 1,831 individuals in the meta-analysis. They found a similar vascular enhancement in IOCM and LOCM, image quality, heart rate variability, and similar risk for patient discomfort. Moreover, IOCM appeared in a slightly lower heart rate by 0.9 bpm.