Dynamic analysis of cardiac rhythms for discriminating atrial fibrillation from lethal ventricular arrhythmias

Circ Arrhythm Electrophysiol. 2013 Jun;6(3):555-61. doi: 10.1161/CIRCEP.113.000034. Epub 2013 May 16.


Background: Implantable cardioverter-defibrillators (ICDs), the first line of therapy for preventing sudden cardiac death in high-risk patients, deliver appropriate shocks for termination of ventricular tachycardia (VT)/ventricular fibrillation. A common shortcoming of ICDs is imperfect rhythm discrimination, resulting in the delivery of inappropriate shocks for atrial fibrillation (AF). An underexplored area for rhythm discrimination is the difference in dynamic properties between AF and VT/ventricular fibrillation. We hypothesized that the higher entropy of rapid cardiac rhythms preceding ICD shocks distinguishes AF from VT/ventricular fibrillation.

Methods and results: In a multicenter, prospective, observational study of patients with primary prevention ICDs, 119 patients received shocks from ICDs with stored, retrievable intracardiac electrograms. Blinded adjudication revealed shocks were delivered for VT/ventricular fibrillation (62%), AF (23%), and supraventricular tachycardia (15%). Entropy estimation of only 9 ventricular intervals before ICD shocks accurately distinguished AF (receiver operating characteristic curve area, 0.98; 95% confidence intervals, 0.93-1.0) and outperformed contemporary ICD rhythm discrimination algorithms.

Conclusions: This new strategy for AF discrimination based on entropy estimation expands on simpler concepts of variability, performs well at fast heart rates, and has potential for broad clinical application.

Keywords: ECG; death, sudden, cardiac; defibrillators, implantable; entropy; inappropriate shock; nonlinear dynamics; tachycardia, ventricular; ventricular fibrillation.

Publication types

  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Atrial Fibrillation / diagnosis*
  • Atrial Fibrillation / mortality
  • Atrial Fibrillation / therapy
  • Death, Sudden, Cardiac / etiology
  • Death, Sudden, Cardiac / prevention & control*
  • Defibrillators, Implantable*
  • Diagnosis, Differential
  • Electrocardiography / methods*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Prospective Studies
  • Risk Assessment
  • Severity of Illness Index
  • Survival Analysis
  • Tachycardia, Ventricular / diagnosis
  • Tachycardia, Ventricular / mortality
  • Tachycardia, Ventricular / therapy
  • Treatment Outcome
  • Ventricular Fibrillation / diagnosis*
  • Ventricular Fibrillation / mortality
  • Ventricular Fibrillation / therapy