The periodic activation and inactivation of various cardiac ion channels enables the regular and synchronous contraction of the heart. Therefore, any disruption of the cardiac ion channel signaling network can result in a change in membrane potential and in the shape of cardiac action potential (AP). As a result, the cardiac excitation-contraction coupling can be modified which may lead to arrhythmias and potential patient death. Local Extracellular Action Potential (LEAP) is a technique which enables non-invasive, label-free monitoring of cardiac action potential in a high-throughput real-time format. In our research, we used the Axion LEAP MEA assay to analyse the effect of various selective and non-selective ion channel inhibitors on cardiac AP by quantification of action potential morphology, repolarization irregularities, and arrhythmic risk factors such as triangulation.