167 Address for correspondence: Gholamreza Davoodi, Associate professor, Department of Electrophysiology, Tehran Heart Center, North Kargar Street, Tehran, 14111713138, Iran. Tel: +98 21 88029600; Fax: +98-021-88029731; e-mail: ghdavoodi@yahoo.com Received 23 November 2012; accepted for publication 31 January 2013. INTRODUCTION The implantable cardioverter /defibrillator (ICD) plays a great role in improving the survival of patients who are at risk for sudden cardiac death 1-2 . Myocardial injury, as detected by the elevation of cardiac specific enzymes, has been reported following ICD insertion due to both device-induced shocks and defibrillation thresh- Detection of myocardial injury due to defibrillation threshold checking after insertion of implantable cardioverter/defibrillators Gholamreza DAVOODI, MD; Vahid MOHAMMADI, MD; Akbar SHAFIEE, MD, MSc; Ali KAZEMISAEID, MD; Saeed SADEGHIAN, MD; Ali VASHEGHANI-FARAHANI, MD; Ahmad YAMINISHARIF, MD Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran. Aims Possible myocardial damage caused by defibrillation threshold (DFT) control and its extent after insertion of implantable cardioverter/defibril- lators (ICD) is still a matter for debate. This study aimed to identify the effect of DFT checking during ICD implantation, compared with permanent pacemaker (PPM) implantation, on the magnitude of myocardial damage as assessed by cardiac troponin-T (cTNT) and CK-MB. Methods and results A total of 133 candidates for ICD implantation were enrolled in the ICD group (mean age 60.66 ± 12.25 years; males 111 [83.5%]) as well as 130 candidates in the PPM group (mean age 69.56 ± 12.86 years; males 64 [49.2%]). DFT was controlled in all of the ICD patients. Serum levels of cTNT and CK-MB were measured at baseline plus 8 and 24 hours following the procedure. The results were adjusted for age, gender, and other confounding factors. The amount of cTNT rise after 8 and 24 hours in the ICD group was significantly higher than in the PPM group (p < 0.001 for both). These differences remained significant after adjustment for confounding factors. The level of CK-MB rise after 8 and 24 hours was also significantly higher in the ICD group, although it lost its significance after adjustment for age, gender and other confounding variables. There was no significant rela- tionship between the amount of energy delivered and enzyme elevation. Conclusion Elevation of cTNT and CK-MB after the ICD implantation was significantly higher than that after the PPM implantation and may be attributed to the DFT testing shock and resulting myocardial injury. Keywords Implantable cardioverter/defibrillator – myocardial injury – defibrillation threshold checking – cardiac troponin T – creatine kinase MB. old (DFT) checking 3-5 . Current data suggest that the elevation of cardiac-specific enzymes following ICD implantation, as an indicator of myocardial damage, can influence the outcome in the treated patients 6-8 . None- theless, the exact relationship between DFT checking and the amount of cardiac specific enzyme release and probable myocardial injury has not been clearly eluci- dated yet. Cardiac-specific troponins have been widely accepted as specific markers of myocardial injury 3 . Cardiac tro- ponin T (cTNT) is known as an important diagnostic and prognostic tool in cardiovascular medicine 9-10 . High cTNT levels are detected in acute coronary syndrome and congestive heart failure as well as many other cardiovascular disorders 11-12 . Moreover, manipulations during electrophysiological interventions can create myocardial injury of various degrees, which is well detected by cardiac troponins 3 . Elevation of creatine kinase-MB after DFT checking has been reported 6 , Acta Cardiol 2013; 68(2): 167-172 doi: 10.2143/AC.68.2.2967274