title: A novel algorithm for individualized cardiac resynchronization therapy: rationale and design of the adaptive cardiac resynchronization therapy trial.
abstract: BACKGROUND
  The magnitude of benefit of cardiac resynchronization therapy (CRT) varies significantly among its recipients; approximately 30% of CRT patients do not report clinical improvement. Optimization of CRT pacing parameters can further improve cardiac function, both acutely and chronically. Echocardiographic optimization is used in clinical practice, but it is time and resource consuming. In addition, optimal settings at rest may change later with activity or cardiac remodeling. The adaptive CRT (aCRT) algorithm was designed to provide automatic ambulatory adjustment of CRT pacing configuration (left ventricular or biventricular pacing) and device delays based on periodic measurement of electrical conduction intervals.
  
  
  METHODS
  The aCRT algorithm is currently undergoing evaluation in a prospective, randomized, double-blinded, worldwide clinical trial. The trial enrolled 522 patients, who satisfied standard clinical indications for a CRT device. Within 2 weeks after the implant, the patients were randomized to aCRT versus echo-optimized biventricular pacing (Echo) settings in 2:1 ratio and followed up at 1-, 3-, 6-, and 12-month postrandomization. The noninferiority primary trial objectives at 6-month postrandomization are to demonstrate that (a) the percentage of aCRT patients who improved in their clinical composite score is at least as high as the percentage of Echo patients; (b) cardiac performance as assessed by echocardiography is similar when using aCRT settings versus echo-optimized settings; and (c) aCRT does not result in inappropriate device settings. First and last patient enrollments occurred in November 2009 and December 2010, respectively.
  
  
  CONCLUSIONS
  The safety and efficacy of the aCRT algorithm will be evaluated in this ongoing clinical trial.
authors.affiliation: Department of Epidemiology & Preventive Medicine, Monash Centre of Cardiovascular Research & Education in Therapeutics, 89 Commercial Road, Melbourne, VIC 3004 Australia. henry.krum@med.monash.edu.au
authors.forename: Henry
authors.initials: H
authors.lastname: Krum
authors.forename: Bernd
authors.initials: B
authors.lastname: Lemke
authors.forename: David
authors.initials: D
authors.lastname: Birnie
authors.forename: Kathy Lai-Fun
authors.initials: KL
authors.lastname: Lee
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Aonuma
authors.forename: Randall C
authors.initials: RC
authors.lastname: Starling
authors.forename: Maurizio
authors.initials: M
authors.lastname: Gasparini
authors.forename: John
authors.initials: J
authors.lastname: Gorcsan
authors.forename: Tyson
authors.initials: T
authors.lastname: Rogers
authors.forename: Alex
authors.initials: A
authors.lastname: Sambelashvili
authors.forename: Amy
authors.initials: A
authors.lastname: Kalmes
authors.forename: David
authors.initials: D
authors.lastname: Martin
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000401:mortality / Q000628:therapy*; D002304:Cardiac Pacing, Artificial / Q000379:methods; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D017147:Defibrillators, Implantable; D004311:Double-Blind Method; D004867:Equipment Design; D004869:Equipment Safety; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000175:diagnosis / Q000401:mortality / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial / Q000592:standards* / Q000639:trends; D057285:Precision Medicine / Q000592:standards / Q000639:trends; D011446:Prospective Studies; D018570:Risk Assessment; D015996:Survival Rate; D016896:Treatment Outcome; D020257:Ventricular Remodeling / Q000502:physiology