Healthy human induced pluripotent stem cell (hiPSC) lines IMR90 and M180 were cultured in mTeSR1 medium on Matrigel-coated plates and were dissociated using ReLeSR. The cells were then transferred onto Reduced Growth Factor (RF)-Matrigel–coated plates for differentiation into hiPSC-derived cardiomyocytes (hiPSC-CM). Differentiation was initiated on day 0 using differentiation medium (RPMI medium [Gibco] supplemented with 1% B27 minus insulin (Gibco) and 6 μmol/L CHIR99201 (Tocris Bioscience) for 2 days. On day 3, the differentiation medium was supplemented with 2.5 μmol/L Wnt-C59 (Tocris Bioscience). The glucose-depletion method was performed on days 11 and 13 by changing of medium to no-glucose RPMI with 1% B27 minus insulin (33 (link)). hiPSC-CM maturation was initiated from day 16 with replating cells onto RF-Matrigel–coated plates and culturing in DMEM containing 5 mmol/L glucose and supplemented with 0.4 mmol/L oleic acid conjugated to BSA, for 1 week (34 (link)). Results from the IMR90 line are presented in Figs. 1 and 2, with key findings confirmed in the M180 line presented in Supplementary Fig. 1.