PARP1 and cardiomyopathy: Our results provide an explanation for the cellular studies that show PARP1 activity inhibitors are detrimental to mtDNA (13) while PARP1 depletion was beneficial in various models of cardiomyopathy (11, 35), and how PARP1 could be beneficial and detrimental to mtBER (11, 13, 18, 19).