Background: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited cardiac arrhythmia syndrome that leads to sudden cardiac death in children and young adults. The most common form of CPVT is caused by autosomal-dominant mutations in the gene encoding cardiac ryanodine receptor type-2 ( RYR2) . Mutations in RYR2 promote excessive calcium (Ca 2+ ) leak from the sarcoplasmic reticulum (SR), triggering potentially lethal arrhythmias. Recently, we demonstrated that the tetracaine derivative EL20 specifically inhibits RYR2, normalizes Ca 2+ handling, and suppresses arrhythmias in a CPVT mouse model. We hypothesized that EL20 will also normalize Ca 2+ handling and arrhythmias in human induced pluripotent stem cell derived cardiomyocytes (iPSC-CMs). Materials/Methods: Blood samples from a child carrying RYR2 mutation R176Q/+ (RQ) and a mutation-negative relative (WT) were collected, processed into peripheral blood mononuclear cells (pBMCs), and reprogrammed into iPSCs using Sendai virus system. Functional iPSC-CMs were derived using Stemdiff TM kit. Differentiation of CMs was validated using qPCR and immunofluorescent staining. Confocal Ca 2+ imaging was used to monitor RyR2 activity. Axiom Biosystem TM microelectrode arrays (MEA) was used to assess arrhythmogenic action potential (AP) and rates. Results: Successfully differentiated CMs showed increased levels of Ca 2+ -handling markers and decreased levels of stem cell markers. Baseline Ca 2+ imaging revealed a 4-fold increase in calcium spark frequency (CaSpF) in RQ iPSC-CMs (3.08±0.58 a.u., n=12) vs. WT (0.69±0.22 a.u., n=13, p<0.01). Strikingly, EL20 normalized CaSpF in RQ iPSC-CMs (0.60±0.16 a.u., n=9, p<0.05 vs. baseline). Furthermore, EL20 decreased the erratic beat period rate of spontaneous APs occurring in RQ iPSC-CMs to a rate similar to WT. Importantly, EL20 had no significant effect on the beat period rate or field potential duration of WT iPSC-CMs. Conclusion: Our results demonstrate that EL20 normalizes Ca 2+ handling and AP beat rate frequency in patient-derived RYR2-R176Q/+ iPSC-CMs with no observed off-target effects, positioning this novel RyR2-inhibitor as a promising therapeutic candidate for treatment of CPVT.