Detection of myocardial injury due to defi brillation threshold checking after insertion of implantable cardioverter/defi brillators

AIMS: Possible myocardial damage caused by defibrillation threshold (DFT) control and its extent after insertion of implantable cardioverter/defibrillators (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 relationship 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.