title: Autonomic dysfunction and new-onset atrial fibrillation in patients with left ventricular systolic dysfunction after acute myocardial infarction: a CARISMA substudy.
abstract: BACKGROUND
  Atrial fibrillation (AF) increases morbidity and mortality in patients with previous myocardial infarction and left ventricular systolic dysfunction. The purpose of this study was to identify patients with a high risk for new-onset AF in this population using invasive and noninvasive electrophysiological tests.
  
  
  METHODS
  The study included 271 patients from the Cardiac Arrhythmias and RIsk Stratification after Myocardial InfArction (CARISMA) study with an acute myocardial infarction (AMI) and left ventricular ejection fraction ≤40% without previous AF at enrollment. Within 21 days after the AMI, an implantable loop recorder was inserted and used to diagnose AF over the 2-year study duration. The following tests were performed: heart rate variability (HRV) and turbulence (HRT) analyses from repeated 24-hour Holter recordings, 2-dimensional (2D)-echocardiograms, exercise test, and programmed electrophysiologic stimulation.
  
  
  RESULTS
  A total of 101 patients (37%) developed AF during the study. Predictive measures included several indexes of HRV including reduced low-frequency (LF) power from spectral HRV analysis (adjusted HR = 1.6, P = 0.034), HRT slope ≤2.5 (HR = 1.6, P = 0.032) and Detrended Fluctuation Analysis (DFA1) from HRV analysis (HR = 1.8, P = 0.011); all are measures of cardiac autonomic nervous system dysfunction. Combined with age >60 years, low values for LF, HRT slope, and DFA1 provided a powerful risk score for prediction of new-onset AF (1-2 points: HR = 4.3, P = 0.001, 3-4 points: HR = 7.0, P < 0.001).
  
  
  CONCLUSIONS
  Abnormal HRV and HRT parameters, which are associated with disturbances in the cardiac autonomic regulation, are associated with increased risk of new-onset AF independently of conventional clinical risk variables.
authors.affiliation: Department of Cardiology, Gentofte University Hospital, Copenhagen, Denmark. chrjoens@gmail.com
authors.forename: Christian
authors.initials: C
authors.lastname: Jons
authors.forename: Pekka
authors.initials: P
authors.lastname: Raatikainen
authors.forename: Uffe J
authors.initials: UJ
authors.lastname: Gang
authors.forename: Heikki V
authors.initials: HV
authors.lastname: Huikuri
authors.forename: Rikke Moerch
authors.initials: RM
authors.lastname: Joergensen
authors.forename: Arne
authors.initials: A
authors.lastname: Johannesen
authors.forename: Ulrik
authors.initials: U
authors.lastname: Dixen
authors.forename: Marc
authors.initials: M
authors.lastname: Messier
authors.forename: Scott
authors.initials: S
authors.lastname: McNitt
authors.forename: Poul Erik Bloch
authors.initials: PE
authors.lastname: Thomsen
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D001341:Autonomic Nervous System / Q000503:physiopathology*; D016009:Chi-Square Distribution; D004452:Echocardiography; D015716:Electrocardiography, Ambulatory; D022062:Electrophysiologic Techniques, Cardiac; D005080:Exercise Test; D005260:Female; D006321:Heart / Q000294:innervation*; D006339:Heart Rate; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000503:physiopathology; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D018570:Risk Assessment; D012307:Risk Factors; D013599:Systole; D013997:Time Factors; D018487:Ventricular Dysfunction, Left / Q000209:etiology* / Q000503:physiopathology