Cardiac organoids enable the assessment of multiple functional and tissue-level cardiac safety endpoints within an integrated model. Depending on the experimental design, they can be used to evaluate electrophysiological changes, calcium handling, contractile function, metabolic alterations, and cardiotoxic responses. Their three-dimensional organization also allows investigation of phenotypes arising from interactions among different cardiac cell types. These features makes cardiac organoids a complementary model for studying complex drug-induced cardiac effects that may be difficult to capture in single-cell or single-channel assays.

Cardiac organoids are not intended to replace hERG screening or 2D hiPSC-CM assays. Instead, they can add a higher level of functional and tissue context to an existing cardiac safety workflow. hERG assays provide information on a specific ion channel, while hiPSC-CMs enable human cardiomyocyte-level assessment of electrophysiology, calcium handling, and contractility. Cardiac organoids further incorporate three-dimensional organization and multicellular interactions, helping researchers investigate whether molecular or cellular changes translate into more complex cardiac phenotypes.

Cardiac organoids are particularly valuable when cardiac safety assessment requires more than a single-channel or single-cell readout. They can support the investigation of complex cardiac phenotypes, integration of multiple functional endpoints, and mechanistic studies of drug-induced cardiotoxicity in a three-dimensional human cell-derived model. They also provide additional human-relevant functional evidence during compound comparison and candidate optimization, complementing data from animal studies, hERG assays, and 2D hiPSC-CM models.

The three-dimensional structure and extended culture period of cardiac organoids enable the assessment of drug effects over longer exposure periods. Under appropriate experimental conditions, repeated dosing and longitudinal measurements can be used to track the development and persistence of cardiac phenotypes over time, including cumulative or delayed effects that may be missed in acute assays. However, the applicability of cardiac organoids to chronic toxicity studies depends on the compound, exposure regimen, culture duration, and endpoints being assessed.

Model selection should be driven by the biological question and the type of cardiac risk being investigated. Ion-channel assays provide targeted molecular information, animal studies capture systemic physiological responses, and 2D hiPSC-CMs enable functional testing at the human cardiomyocyte level . Cardiac organoids provide a three-dimensional tissue context and multicellular interactions. Rather than replacing existing methods, this model can be integrated into a tiered evaluation strategy to generate complementary evidence across molecular, cellular, and tissue levels. Reproducibility, functional validation, experimental consistency, and the intended application should also be considered when selecting an appropriate approach.

Model selection should be driven by the biological question and the type of cardiac risk being investigated. Ion-channel assays provide targeted molecular information, animal studies capture systemic physiological responses, and 2D hiPSC-CMs enable functional testing at the human cardiomyocyte level . Cardiac organoids provide a three-dimensional tissue context and multicellular interactions. Rather than replacing existing methods, this model can be integrated into a tiered evaluation strategy to generate complementary evidence across molecular, cellular, and tissue levels. Reproducibility, functional validation, experimental consistency, and the intended application should also be considered when selecting an appropriate approach.