Troponin levels after ICD implantation with and without defibrillation testing and their predictive value for outcomes: Insights from the SIMPLE trial

• Published in: Heart rhythm Vol. 13; no. 2; pp. 504 - 510
• Main Authors: Vamos, Mate, MD, Healey, Jeff S., MD, FHRS, Wang, Jia, MSc, Duray, Gabor Z., MD, Connolly, Stuart J., MD, van Erven, Lieselot, MD, Vinolas, Xavier, MD, Neuzner, Jorg, MD, Glikson, Michael, MD, FHRS, Hohnloser, Stefan H., MD, FHRS
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.02.2016
• Subjects: Aged; Cardiomyopathies - complications; Cardiomyopathies - mortality; Cardiomyopathies - therapy; Cardiovascular; Death, Sudden, Cardiac - prevention & control; Defibrillation testing; Defibrillators, Implantable - adverse effects; Electric Countershock - instrumentation; Electric Countershock - methods; Female; Humans; Implantable cardioverter-defibrillator; Long QT Syndrome - complications; Long QT Syndrome - mortality; Long QT Syndrome - therapy; Male; Materials Testing - methods; Middle Aged; Mortality; Outcome Assessment (Health Care); Postoperative Complications - blood; Postoperative Complications - diagnosis; Predictive Value of Tests; Prognosis; Prosthesis Implantation - adverse effects; Prosthesis Implantation - methods; Troponin - blood; Troponin I; Troponin T; RR; defibrillation testing; CI; Shockless IMPLant Evaluation; Mortality; HR; ICD; relative risk; Troponin T; DT; upper limit of normal; Troponin I; ULN; hazard ratio; SIMPLE; confidence interval; implantable cardioverter-defibrillator; Implantable cardioverter-defibrillator; Defibrillation testing
• ISSN: 1547-5271; 1556-3871
• DOI: 10.1016/j.hrthm.2015.11.009

Background The Shockless IMPLant Evaluation trial randomized 2500 patients receiving a first implantable cardioverter-defibrillator (ICD)/cardiac resynchronization therapy-defibrillator device to have either defibrillation testing (DT) or no DT. It demonstrated that DT did not improve shock efficacy or reduce mortality. Objective This prospective substudy evaluated the effect of DT on postoperative troponin levels and their predictive value for total and arrhythmic mortality. Methods Troponin levels were measured between 6 and 24 hours after ICD implantation in 2200 of 2500 patients. Results A postoperative serum troponin level above the upper limit of normal (ULN) was more common in patients undergoing DT (n = 509 [46.4%]) than in those not subjected to DT (n = 456 [41.3%]; P = .02). After excluding patients with known preoperative troponin levels above the ULN, consistent findings were observed (42.1% vs 37.5%; P = .04). During a mean follow-up of 3.1 ± 1.0 years, the annual mortality rate was increased in patients with postoperative troponin levels above the ULN (adjusted hazard ratio [HR] 1.43; 95% confidence interval [CI] 1.15–1.76; P = .001) irrespective of DT or no DT. Likewise, patients with elevated troponin levels had a significantly higher risk of arrhythmic death (adjusted HR 1.80; 95% CI 1.23–2.63; P = .002). The rate of first appropriate ICD shock (adjusted HR 0.89; 95% CI 0.71–1.12; P = .32) or failed appropriate shock (adjusted HR 1.02; 95% CI 0.59–1.76; P = .95) was similar in patients with or without troponin elevation. Conclusion DT at the time of ICD implantation is associated with increased troponin levels, indicating subclinical myocardial injury caused by the procedure. Elevated troponin levels but not DT seem to predict clinical outcomes in ICD recipients.