Leak is elevated in the failing heart [23], as well as in conditions characterized by gain-of-function mutations in proteins of the RyR2 macromolecular complex, such as catecholaminergic polymorphic ventricular tachycardia (CPVT) [24,25]. The gene discussed is RYR2; the disease is catecholaminergic polymorphic ventricular tachycardia.