European Heart Journal Advance Access originally published online on March 5, 2009
European Heart Journal 2009 30(8):950-958; doi:10.1093/eurheartj/ehp050
Low-dose dobutamine stress echo to quantify the degree of remodelling after cardiac resynchronization therapy
1 Department of Echocardiography, St George's Hospital, Blackshaw Road, SW17 0QT London, UK
2 ICREA and Universitat Pompeu Fabra (CISTIB), Barcelona, Spain
3 University of Leuven, Belgium
Received 25 August 2008; revised 17 December 2008; accepted 22 January 2009; online publish-ahead-of-print 5 March 2009.
* Corresponding author. Tel: +44 2087251397, Fax: +44 2087254402, Email: chirineparsai{at}hotmail.com
See page 885 for the editorial comment on this article (doi:10.1093/eurheartj/ehp106)
Aims: 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.
Methods and 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.
Conclusion: 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.
Key Words: Dobutamine stress echo • Cardiac resynchronization therapy • Heart failure
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