title: Heart rate turbulence predicts ICD-resistant mortality in ischaemic heart disease.
abstract: OBJECTIVE
  In high-risk patients, implantable cardioverter-defibrillators (ICDs) can convert the mode of death from arrhythmic to pump failure death. Therefore, we introduced the concept of 'ICD-resistant mortality' (IRM), defined as death (a) without previous appropriate ICD intervention (AI), (b) within 1 month after the first AI, or (c) within 1 year after the initial ICD implantation. Implantable cardioverter-defibrillator implantation in patients with a high risk of IRM should be avoided.
  
  
  RESULTS
  Implantable cardioverter-defibrillator patients with ischaemic heart disease were included if a digitized 24 h Holter was available pre-implantation. Demographic, electrocardiographic, echocardiographic, and 24 h Holter risk factors were collected at device implantation. The primary endpoint was IRM. Cox regression analyses were used to test the association between predictors and outcome. We included 130 patients, with a mean left ventricular ejection fraction (LVEF) of 33.6 ± 10.3%. During a follow-up of 52 ± 31 months, 33 patients died. There were 21 cases of IRM. Heart rate turbulence (HRT) was the only Holter parameter associated with IRM and total mortality. A higher New York Heart Association (NYHA) class and a lower body mass index were the strongest predictors of IRM. Left ventricular ejection fraction predicted IRM on univariate analysis, and was the strongest predictor of total mortality. The only parameter that predicted AI was non-sustained ventricular tachycardia.
  
  
  CONCLUSIONS
  Implantable cardioverter-defibrillator implantation based on NYHA class and LVEF leads to selection of patients with a higher risk of IRM and death. Heart rate turbulence may have added value for the identification of poor candidates for ICD therapy. Available Holter parameters seem limited in their ability to predict AI.
authors.affiliation: Department of Cardiology, University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium.
authors.forename: Thomas
authors.initials: T
authors.lastname: Marynissen
authors.affiliation: Department of Cardiology, University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium.
authors.forename: Vincent
authors.initials: V
authors.lastname: Floré
authors.affiliation: Department of Cardiology, University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium.
authors.forename: Hein
authors.initials: H
authors.lastname: Heidbuchel
authors.affiliation: Department of Cardiology, University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium.
authors.forename: Dieter
authors.initials: D
authors.lastname: Nuyens
authors.affiliation: Department of Cardiology, University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium.
authors.forename: Joris
authors.initials: J
authors.lastname: Ector
authors.affiliation: Department of Cardiology, University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium rik.willems@uzleuven.be.
authors.forename: Rik
authors.initials: R
authors.lastname: Willems
mesh_terms: D000368:Aged; D015992:Body Mass Index; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000009:adverse effects / Q000295:instrumentation* / Q000401:mortality; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D017202:Myocardial Ischemia / Q000150:complications* / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology; D018579:Patient Selection; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013318:Stroke Volume; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000209:etiology / Q000401:mortality / Q000628:therapy*; D013997:Time Factors; D017211:Treatment Failure; D016277:Ventricular Function, Left
keywords: Heart rate turbulence; ICD; Ischaemic heart disease; Non-invasive risk stratification; Sudden cardiac death