RYR2 and Arrhythmia: However, only two knockin models were confirmed to exhibit exercise-triggered VTs, RyR2-R2474S+/– (Lehnart et al., 2008) and RyR2-R4496C+/– (Priori and Napolitano, 2005; Liu et al., 2006), and are hence reminiscent of the human arrhythmia phenotype diagnosed by exercise stress testing.