Defibrillation threshold testing: Is it necessary during implantable cardioverter-defibrillator implantation?

Cardiac troponin levels following implantable cardioverter defibrillation implantation and testing

AIMS

Previous studies have reported the defibrillation testing during implantable cardioverter defibrillator (ICD) implantation is associated with elevated cardiac biomarkers and ST-segment electrocardiogram (ECG) changes suggesting that shocks during testing may cause harm. However, the effects of testing have not been isolated from the implant procedure itself, where lead deployment may cause myocardial damage. This prospective study examined high sensitivity troponin T (hs-TnT) levels and ECG changes during ICD implanting alone, ICD implantation with testing and device testing as a stand-alone procedure.

METHODS AND RESULTS

We examined hs-TnT at baseline, and 6-8 h post procedure and 12 lead ECG at baseline, and 30 s, 5 min, and 10 min post right ventricle lead deployment and post defibrillation. There was no significant change in hs-TnT levels in a group of patients (n = 11) undergoing defibrillation testing alone, while hs-TnT was significantly elevated in patients undergoing implantation alone (n = 13, median increase 96%, P = 0.005) and in patients undergoing implantation and testing (n = 13, median increase 161%, P = 0.005). There was a significant correlation between the number of lead deployments and the percentage change in hs-TnT (r = -0.51, P = 0.01), but no correlation between either the number of shocks (r = 0.26, P = 0.25) or the total delivered energy (r = 0.24, P = 0.30) and percentage change in hs-TnT.

CONCLUSION

Implantation of ICD leads was associated with release of troponin, but we did not observe any evidence that ICD shocks alone cause myocardial injury.

Intraoperative defibrillation threshold testing and postoperative long-term efficacy of cardioverter-defibrillator implantation

The aim of this study was to determine the defibrillation threshold (DFT) of implantable cardioverter-defibrillators (ICDs) and outcomes of treatment. Sixty-four patients received cardioverter-defibrillator implantation. During implantation, the DFT was determined by the defibrillation safety margin (DSM). All patients were followed up for 12–48 months after the implantation. The overall DFT was 14.27±2.56 J and the DSM was 18.40±1.89 J. Malignant ventricular arrhythmias occurred in 42 patients following cardioverter-defibrillator implantation including 500 episodes of non-sustained ventricular tachycardia (VT) and 289 episodes of persistent VT. VT was treated using antitachycardia pacing (ATP); 265 episodes were treated successfully by a single ATP treatment (91.69%) and 12 episodes were treated successfully by two ATP treatments (4.15%). Twelve episodes were converted by low-energy electrical cardioversion (4.15%). A total of 175 ventricular fibrillation (VF) episodes were identified, of which 18 episodes automatically terminated prior to treatment. In total, 146 episodes were converted by a single cardioversion with a defibrillation energy of 13.21±2.58 J and 11 episodes were converted by two cardioversions with a defibrillation energy of 16.19±2.48 J. It is safe and feasible to determine the DFT by DSM measurement during cardioverterdefibrillator implantation.