title: Effect of cardiac resynchronization therapy in patients without left intraventricular dyssynchrony.
abstract: OBJECTIVE
  To evaluate the effects of cardiac resynchronization therapy (CRT) on long-term survival of patients without baseline left ventricular (LV) mechanical dyssynchrony.
  
  
  RESULTS
  A total of 290 heart failure patients (age 67 ± 10 years, 77% males) without significant baseline LV dyssynchrony (<60 ms as assessed with tissue Doppler imaging) were treated with CRT. Patients were divided according to the median LV dyssynchrony measured after 48 h of CRT into two groups. All-cause mortality was compared between the subgroups. In addition, the all-cause mortality rates of these subgroups were compared with the all-cause mortality of 290 heart failure patients treated with CRT who showed significant LV dyssynchrony (≥60 ms) at baseline. In the group of patients without significant LV dyssynchrony, median LV dyssynchrony increased from 22 ms (inter-quartile range 16-34 ms) at baseline to 40 ms (24-56 ms) 48 h after CRT. The cumulative mortality rates at 1-, 2-, and 3-year follow-up of patients with LV dyssynchrony ≥40 ms 48 h after CRT implantation were significantly higher when compared with patients with LV dyssynchrony <40 ms (10, 17, and 23 vs. 3, 8, and 10%, respectively; log-rank P< 0.001). Finally, the cumulative mortality rates at 1-, 2-, and 3-year follow-up of patients with baseline LV dyssynchrony were 3, 8, and 11%, respectively (log-rank P= 0.375 vs. patients with LV dyssynchrony <40 ms). Induction of LV dyssynchrony after CRT was an independent predictor of mortality (hazard ratio: 1.247; P= 0.009).
  
  
  CONCLUSIONS
  In patients without significant LV dyssynchrony, the induction of LV dyssynchrony after CRT may be related to a less favourable long-term outcome.
authors.affiliation: Department of Cardiology,  Leiden University Medical Centre, Albinusdreef 2, 2333 ZA Leiden,  The Netherlands.
authors.forename: Dominique
authors.initials: D
authors.lastname: Auger
authors.forename: Gabe B
authors.initials: GB
authors.lastname: Bleeker
authors.forename: Matteo
authors.initials: M
authors.lastname: Bertini
authors.forename: See H
authors.initials: SH
authors.lastname: Ewe
authors.forename: Rutger J
authors.initials: RJ
authors.lastname: van Bommel
authors.forename: Tomasz G
authors.initials: TG
authors.lastname: Witkowski
authors.forename: Arnold C T
authors.initials: AC
authors.lastname: Ng
authors.forename: Lieselot
authors.initials: L
authors.lastname: van Erven
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Schalij
authors.forename: Jeroen J
authors.initials: JJ
authors.lastname: Bax
authors.forename: Victoria
authors.initials: V
authors.lastname: Delgado
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy / Q000401:mortality*; D016022:Case-Control Studies; D015150:Echocardiography, Doppler; D005260:Female; D006333:Heart Failure / Q000401:mortality / Q000628:therapy*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010138:Pacemaker, Artificial; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000401:mortality / Q000628:therapy*