title: Results of the multicenter RENEWAL 3 AVT clinical study of cardiac resynchronization defibrillator therapy in patients with paroxysmal atrial fibrillation.
abstract: BACKGROUND
  Atrial fibrillation impacts the clinical course of up to 50% of patients with advanced heart failure (HF) who are eligible for cardiac resynchronization therapy with a defibrillator (CRT-D). While RV-based defibrillators are available with advanced atrial diagnostics and therapies that provide rapid diagnosis and treatment of spontaneously occurring atrial tachycardia/fibrillation (AT/AF) episodes, there is no CRT-D device that combines atrial/ventricular and CRT therapies.
  
  
  OBJECTIVE
  The purpose of the prospective multicenter RENEWAL 3 AVT study is to assess the performance of atrial diagnostics and therapies used in combination with a CRT-D device.
  
  
  METHODS
  Enrolled patients were required to have indications for a CRT-D device and a documented episode of AT/AF within 12 months of enrollment. A total of 170 patients were enrolled over 9 months (85% male; mean age 72 +/- 10 years; NYHA classification: 88% III, 12% IV; left ventricular ejection fraction [LVEF] mean 23 +/- 6%; mean QRS duration 150 +/- 25 msec; 78% ischemic etiology). The documented atrial arrhythmia was AF in 77% of patients. A total of 60% of patients had the CRT-D device placed for primary prevention of sudden death and 40% of patients had a history of ventricular arrhythmia in addition to HF. The device operates in the biventricular (BiV) triggered mode for sensed ventricular events associated with AF.
  
  
  RESULTS
  A total of 159 patients (95%) had a successful CRT-D implant. Over a mean follow-up of 5.7 +/- 2.3 months, there were a total of 152 atrial shocks delivered in 108 patients for induced (93%) or spontaneous (7%) occurring episodes of AF. Spontaneously occurring AF was observed in 40 patients (25%). The rate of first shock conversion was 118/152 (78%, mean energy 11.6 +/- 5.9 J). Overall shock therapy conversion rate was 138/152 (91%). The number of shock conversions resulting in sinus rhythm maintained for at least 2 minutes postshock was 87% for induced episodes. Therapy was delivered for spontaneous ventricular tachycardia/fibrillation in nine patients (6%). There was no instance of ventricular proarrhythmia associated with atrial shock therapies, undersensing of ventricular arrhythmias, or interruption of CRT therapy associated with the combined device.
  
  
  CONCLUSIONS
  In CRT-D candidates with a history of AF, 25% experience recurrent AF within 6 months of implant. Atrial detection and ventricular detection, shock, and resynchronization therapies are not compromised by the addition of atrial therapies to a CRT-D device.
authors: USC Keck School of Medicine, Los Angeles, California, USA. saxon.usc.edu
authors: Leslie A
authors: LA
authors: Saxon
authors: Ruth Ann
authors: RA
authors: Greenfield
authors: Brian G
authors: BG
authors: Crandall
authors: Charles C
authors: CC
authors: Nydegger
authors: Michael
authors: M
authors: Orlov
authors: Rhonda
authors: R
authors: VAN Genderen