title: Heart rate variability density analysis (Dyx) for identification of appropriate implantable cardioverter defibrillator recipients among elderly patients with acute myocardial infarction and left ventricular systolic dysfunction.
abstract: OBJECTIVE
  Dyx is a new heart rate variability (HRV) density analysis specifically designed to identify patients at high risk for malignant ventricular arrhythmias. The aim of this study was to test if Dyx can improve risk stratification for malignant ventricular tachyarrhythmias and to test if the previously identified cut-off can be reproduced.
  
  
  RESULTS
  This study included 248 patients from the CARISMA study with ejection fraction ≤40% after an acute myocardial infarction and an analysable 24 h Holter recording. All patients received an implantable cardiac monitor, which was used to diagnose the primary endpoint of near-fatal or fatal ventricular tachyarrhythmias likely preventable by an implantable cardioverter defibrillator (ICD), during a period of 2 years. A Dyx ≤ 1.96 was considered abnormal. The secondary endpoint was cardiovascular death. At enrolment 59 patients (24%) had a Dyx ≤ 1.96 and 20 experienced a primary endpoint. A Dyx ≤ 1.96 was associated with a significantly increased risk for malignant arrhythmias [hazards ratio (HR) = 4.36 (1.81-10.52), P = 0.001] and cardiovascular death [HR = 3.47 (1.38-8.74), P = 0.008]. Compared with important clinical risk parameters (age >70 years and QRS > 120 ms), Dyx ≤ 1.96 significantly added predictive value (P = 0.0066).
  
  
  CONCLUSIONS
  Dyx was a better predictor of ventricular tachyarrhythmias than the traditional measures of HRV and heart rate turbulence, particularly in the elderly. Dyx might be a useful tool for better selection of ICD candidates in the elderly population, since a normal Dyx in this group was associated with a very low risk for malignant ventricular arrhythmias.ClinicalTrials.gov Identifier NCT00145119.
authors.affiliation: Department of Cardiology, Copenhagen University Hospital Gentofte, Gentofte, Denmark mojo@dadlnet.dk.
authors.forename: Rikke Mørch
authors.initials: RM
authors.lastname: Jørgensen
authors.affiliation: Ariel University, Samaria, Israel.
authors.forename: Jacob
authors.initials: J
authors.lastname: Levitan
authors.affiliation: Ariel University, Samaria, Israel.
authors.forename: Zohar
authors.initials: Z
authors.lastname: Halevi
authors.affiliation: Ariel University, Samaria, Israel.
authors.forename: Natalia
authors.initials: N
authors.lastname: Puzanov
authors.affiliation: Department of Cardiology, Bispebjerg Hospital, Copenhagen, Denmark.
authors.forename: Steen Zabell
authors.initials: SZ
authors.lastname: Abildstrøm
authors.affiliation: Medtronic Bakken Research Center, Maastricht, The Netherlands.
authors.forename: Marc D
authors.initials: MD
authors.lastname: Messier
authors.affiliation: Department of Internal Medicine, University of Oulu, Oulu, Finland.
authors.forename: Heikki V
authors.initials: HV
authors.lastname: Huikuri
authors.affiliation: Department of Cardiology, Copenhagen University Hospital Gentofte, Gentofte, Denmark.
authors.forename: Jens
authors.initials: J
authors.lastname: Haarbo
authors.affiliation: Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark.
authors.forename: Poul Erik Bloch
authors.initials: PE
authors.lastname: Thomsen
authors.affiliation: Department of Cardiology, Copenhagen University Hospital Gentofte, Gentofte, Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Jons
mesh_terms: D000367:Age Factors; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality / Q000503:physiopathology / Q000517:prevention & control*; D016757:Death, Sudden, Cardiac / Q000209:etiology / Q000517:prevention & control; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000295:instrumentation*; D015716:Electrocardiography, Ambulatory; D005060:Europe; D005260:Female; D006339:Heart Rate; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology; D017711:Nonlinear Dynamics; D018579:Patient Selection; D011237:Predictive Value of Tests; D018570:Risk Assessment; D012307:Risk Factors; D012815:Signal Processing, Computer-Assisted; D013318:Stroke Volume; D013599:Systole; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality / Q000503:physiopathology; D016277:Ventricular Function, Left
keywords: Acute myocardial infarction; CARISMA; Cardiovascular risk; Heart rate variability; Malignant arrhythmias; Multipole analysis