Ventricular fibrillation treated by an implantable cardioverter-defibrillator in antimitochondrial M2 antibody–positive myocarditis

Anti-mitochondrial antibodies, particularly anti-mitochondrial M2 antibodies, are best known as serologic markers of primary biliary cholangitis. However, anti-mitochondrial antibody-positive myositis can be accompanied by clinically important cardiac involvement, including myocarditis, left ventricular dysfunction, conduction disturbance, and ventricular arrhythmias.1-6 Because skeletal muscle symptoms may be mild, patients can initially present to cardiology services with findings that overlap with other inflammatory cardiomyopathies, including isolated cardiac sarcoidosis.