Cardiotoxicity, heart damage caused by certain medications, is a major reason why drugs are withdrawn from the market, even after they’ve been approved. This not only leads to high costs for pharmaceutical companies, but also puts patients at serious risk. Our research aims to address this by creating a more affordable and accessible way to detect heart-related side effects early in drug development, before the drugs reach human testing. Using heart cells grown from stem cells, a lab-based system has been developed that closely mimics real human heart tissue. In this study, a substance called dexamethasone was found to help heart cells develop more mature and realistic characteristics, making them more useful for testing the safety of new drugs. This could significantly improve the reliability of early-stage drug screening. The impact of this work will primarily benefit the pharmaceutical and biotech industries by reducing the risk of late-stage failures and costly drug withdrawals. Importantly, the broader public, including patients and healthcare professionals, will benefit from safer medications. Identifying heart-related side effects at an early stage can help reduce the risk of patients experiencing drug-induced heart damage. This also has the potential to lower healthcare costs for public health authorities, as fewer people would require treatment for preventable cardiotoxic effects. Over time, this approach could contribute to faster, safer, and more cost-effective drug development, reduce reliance on animal testing, and lay the groundwork for personalized safety testing in the future.