It was reported that a decrease or loss of UCP3 in rodent knockout models diminished the contractile heart function, increased ROS production and tissue damage following ischemia (Harmancey et al., 2013; Ozcan et al., 2013; Perrino et al., 2013), whereas other research groups demonstrated that a lack of UCP3 led to a higher death rate in mice due to cardiac arrhythmias upon lipid-challenged conditions (Nabben et al., 2014). Here, UCP3 is linked to cardiac arrhythmia.