Document Detail

Instantaneous effects of resynchronisation therapy on exercise performance in heart failure patients: the mechanistic role and predictive power of total isovolumic time.
MedLine Citation:
PMID:  17085532     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Cardiac resynchronisation therapy improves peak oxygen uptake (peak VO(2)) 3-9 months after device implantation. In chronic heart failure, total isovolumic time (t-IVT) is a major determinant of peak VO(2) and of cardiac output at peak dobutamine stress. In selected patients, resynchronisation can instantaneously shorten t-IVT. We sought to determine the acute effect of resynchronisation on exercise performance and determine, with pharmacological stress echocardiography, the mechanism underlying this effect. METHODS AND RESULTS: Twenty-two patients with resynchronisation were studied within 3 months after device implantation. On a single study day, sequential cardiopulmonary exercise tests were performed during native activation (left bundle branch block) and resynchronisation (atrio-biventricular pacing) in random order. Total-IVT and cardiac output (at rest and peak dobutamine stress) were then measured in each activation mode. Resynchronisation acutely increased peak VO(2) by 1.6 (SD 1.5) ml/kg/min (p<0.001) and shortened peak stress t-IVT by 10 (SD 7) s/min (p<0.001), with the effects in individual patients showing a correlation (r = -0.46, p<0.05). Amongst all measurements during native activation, the best predictor of gain in peak VO(2) from resynchronisation was peak stress t-IVT (r = 0.71, p<0.001) with every increment of 5 s/min of peak stress t-IVT during native activation predicting an 8% gain in peak VO(2). No conventional measures during native activation at rest or on stress (including QRS duration, Tei index, tissue Doppler intraventricular delay, and resting t-IVT) added significant additional information. CONCLUSIONS: In eligible patients, resynchronisation can acutely augment peak VO(2), possibly through a mechanism of t-IVT shortening. Under native activation, long t-IVT during peak stress is the single best predictor of acute resynchronisation-mediated increment in peak VO(2).
T V Salukhe; K Dimopoulos; R Sutton; P Poole-Wilson; M Y Henein; M Morgan; J R Clague; D P Francis
Publication Detail:
Type:  Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't     Date:  2006-11-03
Journal Detail:
Title:  Heart (British Cardiac Society)     Volume:  94     ISSN:  1468-201X     ISO Abbreviation:  Heart     Publication Date:  2008 Jan 
Date Detail:
Created Date:  2007-12-17     Completed Date:  2008-01-23     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9602087     Medline TA:  Heart     Country:  England    
Other Details:
Languages:  eng     Pagination:  59-64     Citation Subset:  AIM; IM    
National Heart and Lung Institute, Imperial College, London, UK.
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MeSH Terms
Cardiac Pacing, Artificial / methods*
Cardiac Volume / physiology*
Echocardiography, Stress / methods
Exercise Test / methods
Exercise Tolerance
Heart Failure / therapy*
Oxygen Consumption / physiology
Stroke Volume / physiology
Comment In:
Heart. 2008 Jan;94(1):4-5   [PMID:  18083944 ]

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