ICD Shock, Not Ventricular Fibrillation, Causes Elevation of High Sensitive Troponin T after Defibrillation Threshold Testing—The Prospective, Randomized, Multicentre TropShock-Trial

Abstract

BackgroundThe placement of an implantable cardioverter defibrillator (ICD) has become routine practice to protect high risk patients from sudden cardiac death. However, implantation-related myocardial micro-damage and its relation to different implantation strategies are poorly characterized.MethodsA total of 194 ICD recipients (64±12 years, 83% male, 95% primary prevention of sudden cardiac death, 35% cardiac resynchronization therapy) were randomly assigned to one of three implantation strategies: (1) ICD implantation without any defibrillation threshold (DFT) testing, (2) estimation of the DFT without arrhythmia induction (modified “upper limit of vulnerability (ULV) testing”) or (3) traditional safety margin testing including ventricular arrhythmia induction. High-sensitive Troponin T (hsTnT) levels were determined prior to the implantation and 6 hours after.ResultsAll three groups showed a postoperative increase of hsTnT. The mean delta was 0.031±0.032 ng/ml for patients without DFT testing, 0.080±0.067 ng/ml for the modified ULV-testing and 0.064±0.056 ng/ml for patients with traditional safety margin testing. Delta hsTnT was significantly larger in both of the groups with intraoperative ICD testing compared to the non-testing strategy (p≤0.001 each). There was no statistical difference in delta hsTnT between the two groups with intraoperative ICD testing (p = 0.179).ConclusionHigh-sensitive Troponin T release during ICD implantation is significantly higher in patients with intraoperative ICD testing using shock applications compared to those without testing. Shock applications, with or without arrhythmia induction, did not result in a significantly different delta hsTnT. Hence, the ICD shock itself and not ventricular fibrillation seems to cause myocardial micro-damage.Trial RegistrationClinicalTrials.gov NCT01230086

2015 HRS/EHRA/APHRS/SOLAECE expert consensus statement on optimal implantable cardioverter-defibrillator programming and testing

“…Although an increase in biochemical markers of myocardial injury can be observed during ICD implantation or after spontaneous clinical shocks, true intraoperative myocardial infarction (MI) is rare, even when extensive DT is performed [202][203][204][205]. In 2 recent studies using transvenous ICDs and a more abbreviated testing protocol, there was no significant increase in CK, CK-MB, myoglobin, and NT-proBNP before and after DT, whereas elevated levels of high-sensitive troponin T were observed after DT [206,207]. In the NCDR ICD Registry, the incidence of MI during ICD implantation was reported to be 0.02% [196].…”

Acute Effects of Implantable Cardioverter‐Defibrillator Shocks on Biomarkers of Myocardial Injury, Apoptosis, Heart Failure, and Systemic Inflammation

“…However, a recent animal study does not support this hypothesis since shocks from subcutaneous defibrillators associated with VF induction, and expected longer VF detection time, were not associated with troponin increase . This was confirmed in the TropShock‐Trial, where DFT with or without arrhythmia induction (upper limit of vulnerability in the latter case) increased troponin . Therefore, the most likely mechanism for troponin elevation associated with DFT testing is electroporation, although limited myocardial necrosis cannot be ruled out.…”

“…17 This was confirmed in the TropShock-Trial, where DFT with or without arrhythmia induction (upper limit of vulnerability in the latter case) increased troponin. 18 Therefore, the most likely mechanism for troponin elevation associated with DFT testing is electroporation, 19,20 although limited myocardial necrosis cannot be ruled out. In addition, the magnitude of cTnI peak levels was small, less than 1 ng/mL following implantation (25-fold the upper limit of normal) in 38/40 (95%) patients and less than 50-fold the upper limit of normal (2 ng/mL) in all patients.…”

Wszczepialne kardiowertery-defibrylatory — czy test skuteczności defibrylacji jest jeszcze potrzebny?

“…[19] w metaanalizie obejmującej 8 dużych badań (łącznie 5020 pacjentów ze średnim czasem obserwacji wynoszącym 24 miesiące) nie wykazali, aby wykonanie DT w czasie implantacji ICD miało wpływ na śmiertelność ogólną i z przyczyn arytmicznych w obserwacji odległej; -test defibrylacji może wiązać się z ryzykiem powikłań -potencjalne ryzyko powikłań DT wynika łącznie ze wszystkich zasadniczych elementów protokołu [2]. Wyindukowane VF, wyładowanie wysokoenergetyczne, a także konieczność przeprowadzenia znieczulenia ogólnego mogą prowadzić do rozkojarzenia elektryczno-mechanicznego oraz opornego na terapię VF [20], uszkodzenia miokardium ze wzrostem stę-żenia troponin sercowych [21] oraz upośledzeniem czynności skurczowej w efekcie ogłuszenia mięśnia sercowego [22], hipoperfuzji ośrodkowego układu nerwowego [23] oraz powikłań zakrzepowo-zatorowych w konsekwencji nieadekwatnej antykoagulacji [24]. Największe badanie obserwacyjne (19 067 zabiegów implantacji ICD) oceniające ryzyko wykonania DT przeprowadzili Birne i wsp.…”