In the present study, we found that an increase in elongated mitochondria at 4 h after cardiac arrest was accompanied by a concomitant increase in expression of the fusion proteins Mfn1 and Mfn2, along with a decrease in fission protein Drp1 and Fis1 levels, whereas opposite trend occurred at 12 h and 24 h after cardiac arrest, especially at 24 h. Here, FIS1 is linked to cardiac arrest.