Functional properties for cardiac organoids based on enriched cardiomyocytes at different stimulation modes: (1) no stimulation, (2) monophasic square pulses at 5 V/cm, 1 Hz, and duration of 2 ms, and (3) biphasic square pulses at 2.5 V/cm, 1 Hz, and duration of 1 ms. (A) Excitation threshold. (B) Maximum capture rate. (C) Success rate. Asterisks (*) denote statistically significant difference (p < 0.05; one-way ANOVA with post hoc Tukey's test).