Effects of Implantable Cardioverter Defibrillator Implantation and Shock Application on Biochemical Markers of Myocardial Damage (Heart Health and Clinical Laboratory‪)‬

The Implantation of an implantable cardioverter defibrillator (ICD)[3] is a common approach in patients with ventricular tachycardia or who have survived cryptogenic sudden cardiac death (1). To check for normal ICD function, it is necessary to test the system and to determine the defibrillation threshold. The defibrillation threshold is defined as the lowest energy, in joules (J), for defibrillation of induced ventricular fibrillation (VF). However, repeated episodes of electrical therapy can have disadvantageous effects on myocardial performance (2, 3). The cardiac isoforms of troponin T (cTnT) and troponin I (cTnI) are highly specific markers for the detection of myocardial damage. After myocardial ischemia but also as a result of other myocardial stress, such as myocarditis, cTnI and cTnT are released into the circulation (4, 5) where they can be detected with sensitive immunoassays (6, 7).