Field potential duration and its variability as essential parameters for revealing proarrhythmia: problematic aspects of analysis in cardiomyocytes derived from human pluripotent stem cells

The microelectrode array (MEA) is an easy, high-throughput method, ideal for obtaining a large amount of data from excitable cells, including cardiomyocytes. However, the analysis can be problematic, especially the analysis of the field potential duration (FPD). Several factors, including the differentiation protocol, culture duration, recording settings, and signal processing, may influence the results. In this paper, we focused on the MEA recording settings, analysis, and evaluation of FPD from cardiomyocytes, especially those derived from human pluripotent stem cells (hPSC). By examining more than 120 original articles using MEA and any cardiac preparation, we detected an inconsistency in the acquisition setting. It is striking that only one-third of the studies provided complete information about filtering of the signal, even though this may substantially influence the shape of the signal and, thus, FPD. The performed analysis emphasizes a thorough inspection of both the 'raw' and filtered signals to estimate proper FPD values, as well as a careful determination of the relationship between FPD and cycle length before using any correction formula.