title: Low-dose dobutamine stress echo to quantify the degree of remodelling after cardiac resynchronization therapy.
abstract: OBJECTIVE
  Presence of contractile reserve during low-dose dobutamine stress echo (DSE) appears predictive of cardiac resynchronization therapy (CRT) outcome. We hypothesize that changes in left bundle branch block (LBBB)-induced dyssynchronous motion during low-dose DSE could be related to the extent of reverse remodelling.
  
  
  RESULTS
  Fifty-two patients (69 +/- 2 years, EF: 24 +/- 7%, QRS > 120 ms) were studied pre- and post-CRT (7 +/- 1 months). Reduction in left ventricular end-systolic volume (LVESV) >/=10% defined response. A clinical improvement was sought additionally prior to implant and after CRT (NYHA class reduction >1), increase in 6 min walk test (>10%), and fall in BNP (>/=30%). To identify the presence of septal scar and its impact on our assessment during low-dose DSE, a cardiac magnetic resonance was performed pre-CRT. Presence of an abnormal short-lived septal motion occurring during the isovolumic contraction time [septal flash (SF)] identified LBBB-induced dyssynchrony. Septal flash extent was quantified from M-mode and radial velocity traces. At baseline, 31/52 patients had an SF. In all patients, DSE increased SF. Twenty-nine out of thirty-one patients responded with reverse remodelling post-CRT. The degree of peak low-dose stress SF correlated with the extent of reverse remodelling (R = 0.6, P < 0.0001). Additionally, SF increase correlated with greater fall in BNP post-CRT (R = 0.4, P = 0.01). Among patients with no SF at rest (21/52 patients), low-dose DSE induced an SF and a fall in stroke volume (SV) in five patients who all showed reverse remodelling after CRT. With low-dose DSE, the remaining 16 patients all failed to demonstrate a SF, and all but one patient with additional atrioventricular dyssynchrony were non-responders.
  
  
  CONCLUSIONS
  Low-dose DSE increases and unmasks LBBB-induced dyssynchronous motion, easing its detection. The degree of clinical and echocardiographic response correlated with the extent of peak SF seen during low-dose DSE.
authors.affiliation: Department of Echocardiography, St George's Hospital, Blackshaw Road, SW17 0QT London, UK.
authors.forename: Chirine
authors.initials: C
authors.lastname: Parsai
authors.forename: Aigul
authors.initials: A
authors.lastname: Baltabaeva
authors.forename: Lisa
authors.initials: L
authors.lastname: Anderson
authors.forename: Marinela
authors.initials: M
authors.lastname: Chaparro
authors.forename: Bart
authors.initials: B
authors.lastname: Bijnens
authors.forename: George R
authors.initials: GR
authors.lastname: Sutherland
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D002304:Cardiac Pacing, Artificial; D002316:Cardiotonic Agents / Q000008:administration & dosage; D004298:Dopamine / Q000008:administration & dosage; D025401:Echocardiography, Stress / Q000379:methods; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D011446:Prospective Studies; D013318:Stroke Volume / Q000502:physiology; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000503:physiopathology; D020257:Ventricular Remodeling / Q000502:physiology*
chemical_list: D002316:Cardiotonic Agents; D004298:Dopamine