Heart Failure with preserved ejection fraction (HFpEF) has a high rate of sudden cardiac death (SCD) and empirical treatment is ineffective. We developed a novel preclinical model of metabolic HFpEF that presents with stress-induced ventricular tachycardia (VT). Mechanistically, we discovered arrhythmogenic changes in intracellular Ca 2+ handling distinct from the changes pathognomonic for heart failure with reduced ejection fraction. We further show that dantrolene, a stabilizer of the ryanodine receptor Ca 2+ channel, attenuates HFpEF-associated arrhythmogenic Ca 2+ handling in vitro and suppresses stress-induced VT in vivo. We propose ryanodine receptor stabilization as a mechanistic approach to mitigation of malignant VT in metabolic HFpEF.