title: Effects of physical exercise on cardiac dyssynchrony in patients with impaired left ventricular function.
abstract: OBJECTIVE
  The purpose of this study was to determine the effect of exercise on dyssynchrony in patients with left ventricular dysfunction.
  
  
  RESULTS
  Sixty patients with a left ventricular ejection fraction (LVEF) ≤ 35% were studied. Interventricular mechanical delay (IVMD), intraventricular mechanical delay [Ts-(lateral-septal)], and left ventricular filling ratio were measured at rest and during exercise. Significant IVMD was defined as a difference between aortic and pulmonary pre-ejection times of >40 ms. Intraventricular dyssynchrony was defined as a Ts-(lateral-septal) >65 ms. Forty-five patients with no dyssynchrony at rest were analysed (age 62 ± 14; LVEF 28 ± 6%) and compared with a control group of 15 patients with known dyssynchrony at rest. None of the 45 patients without dyssynchrony at rest developed dyssynchrony during exercise based on IVMD and Ts-(lateral-septal). In the control group, IVMD decreased from 65 ± 19 to 33 ± 11 ms (P< 0.001) during exercise, whereas Ts-(lateral-septal) did not change. Persistence of dyssynchrony during exercise (decrease of IVMD <60%) was significantly associated with response to cardiac resynchronization therapy (CRT). Whereas all 10 responders had persistent dyssynchrony during exercise, 4 of the 5 non-responders (80%) had an exercise-induced decrease of IVMD >60% (P< 0.004).
  
  
  CONCLUSIONS
  Exercise does not elicit mechanical dyssynchrony in patients without dyssynchrony at rest. In patients with significant dyssynchrony at rest, exercise-induced decrease of IVMD is common. Persistence of dyssynchrony during exercise might be a novel predictor of response to CRT.
authors.affiliation: Division of Cardiology, University Hospital Basel, Petersgraben 4, 4031 Basel, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Kühne
authors.forename: Robert
authors.initials: R
authors.lastname: Blank
authors.forename: Beat
authors.initials: B
authors.lastname: Schaer
authors.forename: Peter
authors.initials: P
authors.lastname: Ammann
authors.forename: Stefan
authors.initials: S
authors.lastname: Osswald
authors.forename: Christian
authors.initials: C
authors.lastname: Sticherling
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D058406:Cardiac Resynchronization Therapy; D016022:Case-Control Studies; D004562:Electrocardiography; D015444:Exercise / Q000502:physiology*; D005260:Female; D006333:Heart Failure / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012146:Rest / Q000502:physiology; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology* / Q000628:therapy*