title: Effect of cardiac resynchronization therapy on beat-to-beat T-wave amplitude variability.
abstract: OBJECTIVE
  T-wave amplitude variability (TAV) is a promising non-invasive predictor of arrhythmic events in patients with dilated cardiomyopathy. We aimed to evaluate the effect of cardiac resynchronization therapy (CRT) on native TAV, its relation with left ventricular (LV) reverse remodelling and the occurrence of ventricular tachyarrhythmias (VTs).
  
  
  RESULTS
  In this prospective study, we included 40 heart failure patients with left bundle branch block in sinus rhythm (25 male; 16 with ischaemic aetiology; aged 62.7 ± 9.5 years; New York Heart Association class II-IV). Echocardiographic parameters and TAV were evaluated at baseline and 6 months after implantation of CRT device combined with an implantable cardioverter-defibrillator. T-wave amplitude variability was determined by a 20-min high-resolution electrocardiogram Holter recording during native conduction. After TAV assessment, patients were monitored for 15.7 ± 5.2 months for the occurrence of VTs. Decrease in median TAV [from 40.45 μV (24.75-56.00) to 28.15 μV (20.93-37.95), P = 0.004] was observed after 6 months of CRT. However, decrease of median TAV was only noticed in patients with LV reverse remodelling [46.9 μV (27.5-70.0) to 25.8 μV (20.2-32.4), P < 0.001] and in patients without VTs [40.5 μV (27.5-55.9) to 24.4 μV (17.1-31.5), P < 0.001]. Native median TAV > 35.4 µV after 6 months of CRT had an 83% sensitivity and 93% specificity for predicting the occurrence of VTs.
  
  
  CONCLUSIONS
  Decrease of TAV after CRT is associated with LV reverse remodelling and indicates a reduction of the intrinsic arrhythmogenic substrate. Median TAV after CRT had a good predicting value for VT occurrence in long-term follow-up.
authors.affiliation: Department of Cardiology, University Medical Centre Ljubljana, Zaloška 7, 1000 Ljubljana, Slovenia. davidzizek@yahoo.com
authors.forename: David
authors.initials: D
authors.lastname: Žižek
authors.forename: Marta
authors.initials: M
authors.lastname: Cvijić
authors.forename: Jerneja
authors.initials: J
authors.lastname: Tasič
authors.forename: Matevž
authors.initials: M
authors.lastname: Jan
authors.forename: Sabina
authors.initials: S
authors.lastname: Frljak
authors.forename: Igor
authors.initials: I
authors.lastname: Zupan
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D058406:Cardiac Resynchronization Therapy; D058409:Cardiac Resynchronization Therapy Devices; D017147:Defibrillators, Implantable; D004452:Echocardiography; D015716:Electrocardiography, Ambulatory; D005260:Female; D006333:Heart Failure / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left; D020257:Ventricular Remodeling