“…It has been known for several decades that APD alternans is suppressed or inhibited by verapamil (Marcantoni et al, 2019), caffeine (Wang et al, 2014), BayK8644 (Saitoh et al, 1988), nisoldipine (Saitoh et al, 1988), and ryanodine (Sun et al, 2018), all of which point to a mechanism related to [Ca 2+ ] i handling. Substantial follow-up studies have suggested that disturbances in every-other-beat [Ca 2+ ] i cycling constitute the main cause of AP alternans (Picht et al, 2006;Wang et al, 2014;Sun et al, 2018;Liu et al, 2019;Oropeza-Almazan and Blatter, 2020).…”