The association between defibrillation shock energy and acute cardiac damage in patients with implantable cardioverter defibrillators

Background The aim of this study was to establish a minimally invasive defibrillation testing (DT) protocol for patients with implantable cardioverter defibrillators (ICDs). Methods Two different energy DTs were performed, immediately after (15 J‐DT) and 7 days after (≤10 J‐DT) device implantation, in 20 consecutive ICD implantation patients. Cardiac‐troponin T (c‐TNT) and heart‐type fatty acid binding protein (H‐FABP) levels were measured before implantation, 2 h after implantation, and 1 day after each DT. For an additional 122 patients with ICD, we retrospectively analyzed 203 DTs immediately and 7 days after device implantation. Results Serum c‐TNT levels were significantly elevated 2 h after 15 J‐DT [0.008 (0.004–0.019) vs. 0.053 (0.037–0.068) ng/mL, p <0.001], but not ≤10 J‐DT [0.007 (0.004–0.018) ng/mL]. Similarly, serum H‐FABP levels were significantly elevated 2 h after 15 J‐DT (2.9±1.5 vs. 6.4±3.4 ng/mL, p <0.001), but not ≤10 J‐DT (2.7±1.5 ng/mL). The changes in c‐TNT and H‐FABP levels between baseline and 2 h after DT were significantly greater for 15 J‐DT compared with ≤10 J‐DT [c‐TnT: 0.039 (0.029–0.060) vs. 0 (0–0.003) ng/mL, p <0.001; H‐FABP: 3.6±2.8 vs. −0.16±1.1 ng/mL, p <0.001]. The success rates of the initial shocks delivered for ventricular fibrillation were no different between ≤10 J‐DT (85% [78/92]) and ≥15 J‐DT (92% [103/111]). Conclusions Elevated levels of myocardial damage markers such as c‐TNT and H‐FABP were not found after ≤10 J‐DT. In addition, an acceptable success rate was confirmed in ≤10 J‐DT.