title: Worsening of left ventricular end-systolic volume and mitral regurgitation without increase in left ventricular dyssynchrony on acute interruption of cardiac resynchronization therapy.
abstract: BACKGROUND
  Responders to cardiac resynchronization therapy (CRT) have greater left ventricular (LV) dyssynchrony than nonresponders prior to CRT.
  
  
  OBJECTIVE
  We conducted this study to see whether the long term responders have more worsening of LV dyssynchrony and LV function on acute interruption of CRT.
  
  
  METHODS
  We identified 22 responders and 13 nonresponders who received CRT as per standard criteria for 23.73 +/- 7.9 months (median 24.5 months). We assessed the acute change in LV function, mitral regurgitation (MR) and compared LV dyssynchrony in CRT on and off modes.
  
  
  RESULTS
  On turning off CRT, there was no significant worsening of LV dyssynchrony in both responders and nonresponders. The dyssynchrony measurements by SPWMD, TDI and 3D echocardiography did not correlate significantly. LVESV increased (p = 0.02) and MR (p = 0.01) worsened in CRT-off mode in responders only without significant change in LVEF or LV dimensions.
  
  
  CONCLUSIONS
  In long-term responders to CRT, there is alteration in the function of remodeled LV with acute interruption of CRT, without significant worsening of LV dyssynchrony. The role of different echocardiographic parameters in the assessment of LV dyssynchrony remains controversial. Even after long-term CRT reversely remodels the LV, the therapy needs to be continued uninterrupted for sustained benefits.
authors: Stanford University, Palo Alto, California, USA. sumans@yahoo.com
authors: Suman S
authors: SS
authors: Kuppahally
authors: Michael B
authors: MB
authors: Fowler
authors: Randall
authors: R
authors: Vagelos
authors: Paul
authors: P
authors: Wang
authors: Amin
authors: A
authors: Al-Ahmad
authors: Allan
authors: A
authors: Paloma
authors: David
authors: D
authors: Liang
mesh_terms: D002304:Cardiac Pacing, Artificial / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging* / Q000209:etiology* / Q000517:prevention & control; D013318:Stroke Volume; D016896:Treatment Outcome; D014463:Ultrasonography; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology* / Q000517:prevention & control