title: Echocardiographic study of the optimal atrioventricular delay at rest and during exercise in recipients of cardiac resynchronization therapy systems.
abstract: BACKGROUND
  It is unclear whether, in recipients of cardiac resynchronization therapy (CRT) systems, the optimal AV delay should be the same, shorter, or longer during exercise than at rest.
  
  
  OBJECTIVE
  This study sought to examine the effects of atrioventricular (AV) delay optimization at rest and during exercise in 50 recipients of CRT systems.
  
  
  METHODS
  We measured left ventricular (LV) outflow tract velocity time integral (OT-VTI) and LV filling time (FT) echocardiographically, at rest and during exercise to 60% of the maximal predicted heart rate, with the sensed AV delay set at 40, 70, 100, 120, 150, and 200 ms. The measurements made at rest versus those made during exercise, and among the several programmed AV delays, were compared.
  
  
  RESULTS
  The optimal AV delay based on LVOT-VTI was shorter during exercise than at rest in 37%, unchanged in 37%, and longer in 26% of patients. The optimal AV delay based on LVFT was shorter during exercise than at rest in 27%, unchanged in 23%, and longer in 50% of patients. Optimization of the AV delay during exercise increased LVFT and LVOT-VTI significantly (P < .05) compared with (1) any other arbitrarily chosen AV delay, (2) the optimal AV delay at rest, (3) an AV delay systematically shortened from rest to exercise.
  
  
  CONCLUSIONS
  Optimization of the AV delay had a positive effect on echocardiographic indices of LV function. The systematic shortening of the AV delay during exercise is not recommended because, in a high proportion of patients, the optimal AV delay was longer during exercise than at rest.
authors: University Victor Segalen, 33000 Bordeaux, France.
authors: Bilel
authors: B
authors: Mokrani
authors: Stephane
authors: S
authors: Lafitte
authors: Antoine
authors: A
authors: Deplagne
authors: Sylvain
authors: S
authors: Ploux
authors: Julien
authors: J
authors: Laborderie
authors: Patricia
authors: P
authors: Reant
authors: Pierre
authors: P
authors: Dos Santos
authors: Raymond
authors: R
authors: Roudaut
authors: Pierre
authors: P
authors: Jais
authors: Michel
authors: M
authors: Haissaguerre
authors: Jacques
authors: J
authors: Clementy
authors: Pierre
authors: P
authors: Bordachar
mesh_terms: D000368:Aged; D001283:Atrioventricular Node / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D004452:Echocardiography; D004567:Electrodes, Implanted; D015444:Exercise / Q000502:physiology*; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D011446:Prospective Studies; D012146:Rest / Q000502:physiology*