Ratiometric Fura-2 AM imaging reveals elevated diastolic Ca2+ in hypertrophic cardiomyopathy (HCM) induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). (A) Representative traces of Fura-2 ratiometric Ca2+ imaging. (B and C) HCM iPSC-CMs showed elevated diastolic Ca2+ (B) and prolonged Ca2+ recycling (C) compared with Ctrl iPSC-CMs by one-way ANOVA (Tukey method). N = 51, 42, 43, and 72 cells in Ctrl, MYH7, MYBPC3, and TNNT2 groups, respectively. For each group, data were generated from two different iPSC lines and three batches of differentiation. (D) Representative traces of SR Ca2+ load measurement by caffeine-induced Ca2+ transient. (E and F) Caffeine-induced transient showed higher SR Ca2+ content (E) and slightly decreased caffeine-transient decay-Tau (F) in HCM iPSC-CMs compared with Ctrl iPSC-CMs by one-way ANOVA (Tukey method). N = 22, 28, 25, and 26 cells in Ctrl, MYH7, MYBPC3, and TNNT2 groups, respectively. For each group, data were generated from two different iPSC lines and two batches of differentiation.