Fig. 2.

Incidence of Ca²⁺ alternans in control (Ctrl) and DCM-TnT-R173W induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM). A Normalised representative traces of Ca²⁺ transients (CaT) at 0.5 Hz (upper), 2 Hz (middle) and 5 Hz (lower) in Ctrl (left) and TnT-R173W (right) iPSC-CM. 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 CaT alternans is shown in boxes above. D Kaplan–Meier plot showing the percentage of cells without alternans in relation to the respective pacing frequency. n = number of iPSC-CM from three batches. Data are mean ± SEM. **P < 0.01 and ***P < 0.001 vs. Ctrl using Student’s t test (B), Mann–Whitney U test (C) and the Gehan–Breslow–Wilcoxon test (D)