Background <p>Atrial fibrillation often presents with heart failure. In the clinic, the identification of the sequence of events of the two diseases is difficult using the clinical history. Ferroptosis regulators play a role in heart failure induced atrial fibrillation and have potential to be therapeutic targets in identifying the sequence of events of the two diseases.</p> Methods <p>Ferroptosis mediators retrieved from the FerrDb (v2) database and mediators that had been validated in humans were retained and two-step Mendelian randomization with the delta method (median MR analysis) was performed to find out the mediators in the subsequent occurrence of the two diseases. Six gene expression array datasets (GSE143924, GSE115574, GSE41177, GSE2240, GSE66724, and GSE235307) were retrieved from Gene Expression Omnibus to identify the functional significance of the meaningful regulators identified in the MR analysis in alternating the pathways involved in the pathogenesis of atrial fibrillation. Pathways were analyzed by the Gene Set Enrichment Analysis (GSEA) and single sample (ss)GSEA methods to calculate the enrichment score.</p> Results <p>The median MR analysis identified two ferroptosis drivers (<i>PEX2</i> and <i>YY1AP1</i>) and two ferroptosis suppressors (<i>PTPMT1</i> and <i>CNR1</i>) that have a mediator role in heart failure-induced atrial fibrillation. Further Kyoto Encyclopedia of Genes and Genomes and Reactome annotated pathway enrichment analyses indicated that, except for <i>CNR1</i>, the genes were related to pathways involved in the pathogenesis of atrial fibrillation, with most related to immune environment regulation. Of them, <i>PTPMT1</i> and <i>PEX2</i> were protective factors against atrial fibrillation, whereas <i>YY1AP1</i> promotes atrial fibrillation via upregulating immune reaction activation pathways, including interleukin signaling pathways and leukocyte trans-endothelium migration pathways.</p> Conclusion <p>Ferroptosis regulators are potential therapeutic targets for atrial fibrillation. Heart failure causes atrial fibrillation via the upregulation of <i>YY1AP1. PEX2</i> is a protective factor against atrial fibrillation; its expression level was downregulated in heart failure. <i>PTPMT1</i> is a previously reported cardiovascular protective factor in response to external harmful elements, which showed an increased expression in heart failure. Thus, these ferroptosis regulators played a mediating role in the sequential occurrence of heart failure-induced atrial fibrillation.</p>