Fig. 8.

Incidence of Ca²⁺ alternans in DCM-TnT-R173W induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM) pre-treated with blebbistatin (10 µM). A Normalised representative traces of Ca²⁺ transients (CaT) at 0.5 Hz (upper), 2 Hz (middle) and 5 Hz (lower) in untreated TnT-R173W iPSC-CM (left) and in TnT-R173W iPSC-CM pre-treated with blebbistatin (right). Arrowheads indicate electrical stimulation and illustrate when beat-to-beat alterations are present. B Ca²⁺ transient time constant of decay (τ). C Alternans threshold frequency. Number of myocytes without alternans is shown in boxes above. D Kaplan–Meier plot showing the percentage of cells without alternans in relation to the respective pacing. n = number of iPSC-CM from two batches. Data are mean ± SEM. **P < 0.01 vs. Ctrl using the Mann–Whitney U test (B, C), and the Gehan–Breslow–Wilcoxon test (D)