title: Usefulness and limitation of dobutamine stress echocardiography to predict acute response to cardiac resynchronization therapy.
abstract: BACKGROUND
  It has been hypothesized that a long-term response to cardiac resynchronization therapy (CRT) could correlate with myocardial viability in patients with left ventricular (LV) dysfunction. Contractile reserve and viability in the region of the pacing lead have not been investigated in regard to acute response after CRT.
  
  
  METHODS
  Fifty-one consecutive patients with advanced heart failure, LV ejection fraction <or= 35%, QRS duration > 120 ms, and intraventricular asynchronism >or= 50 ms were prospectively included. The week before CRT implantation, the presence of viability was evaluated using dobutamine stress echocardiography. Acute responders were defined as a >or=15% increase in LV stroke volume.
  
  
  RESULTS
  The average of viable segments was 5.8 +/- 1.9 in responders and 3.9 +/- 3 in nonresponders (P = 0.03). Viability in the region of the pacing lead had an excellent sensitivity (96%), but a low specificity (56%) to predict acute response to CRT. Mitral regurgitation (MR) was reduced in 21 patients (84%) with acute response. The presence of MR was a poor predictor of response (sensibility 93% and specificity 17%). However, combining the presence of MR and viability in the region of the pacing lead yields a sensibility (89%) and a specificity (70%) to predict acute response to CRT.
  
  
  CONCLUSIONS
  Myocardial viability is an important factor influencing acute hemodynamic response to CRT. In acute responders, significant MR reduction is frequent. The combined presence of MR and viability in the region of the pacing lead predicts acute response to CRT with the best accuracy.
authors.affiliation: Department of Cardiology, Institut de Cardiologie de Québec, Hôpital Laval, Québec, Canada. mario.senechal@crhl.ulaval.ca
authors.forename: Mario
authors.initials: M
authors.lastname: Sénéchal
authors.forename: Patrizio
authors.initials: P
authors.lastname: Lancellotti
authors.forename: Patrick
authors.initials: P
authors.lastname: Garceau
authors.forename: Jean
authors.initials: J
authors.lastname: Champagne
authors.forename: Michelle
authors.initials: M
authors.lastname: Dubois
authors.forename: Julien
authors.initials: J
authors.lastname: Magne
authors.forename: Louis
authors.initials: L
authors.lastname: Blier
authors.forename: Frank
authors.initials: F
authors.lastname: Molin
authors.forename: François
authors.initials: F
authors.lastname: Philippon
authors.forename: Jean G
authors.initials: JG
authors.lastname: Dumesnil
authors.forename: Luc
authors.initials: L
authors.lastname: Pierard
authors.forename: Gilles
authors.initials: G
authors.lastname: O'Hara
mesh_terms: D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004280:Dobutamine; D004452:Echocardiography / Q000379:methods*; D005080:Exercise Test / Q000379:methods; D005260:Female; D006333:Heart Failure / Q000150:complications / Q000000981:diagnostic imaging* / Q000517:prevention & control*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D014665:Vasodilator Agents; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology / Q000517:prevention & control*
chemical_list: D014665:Vasodilator Agents; D004280:Dobutamine