Document Detail

Dynamic dyssynchrony and impaired contractile reserve of the left ventricle in beta-thalassaemia major: an exercise echocardiographic study.
MedLine Citation:
PMID:  23028894     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Performance of the left ventricle during exercise stress in thalassaemia patients is uncertain. We aimed to explore the phenomenon of dynamic dyssynchrony and assess contractile reserve in patients with beta-thalassaemia major and determine their relationships with myocardial iron load.
METHODS AND RESULTS: Thirty-two thalassaemia patients (16 males), aged 26.8 ± 6.9 years, without heart failure and 17 healthy controls were studied. Their left ventricular (LV) volumes, ejection fraction, systolic dyssynchrony index (SDI), and myocardial acceleration during isovolumic LV contraction (IVA) were determined at rest and during submaximal bicycle exercise testing using 3-dimensional and tissue Doppler echocardiography. Myocardial iron load as assessed by T2* cardiac magnetic resonance in patients were further related to indices of LV dyssynchrony and contractile reserve. At rest, patients had significantly greater LV SDI (p<0.001) but similar IVA (p = 0.22) compared with controls. With exercise stress, the prevalence of mechanical dyssynchrony (SDI>4.6%, control+2SD) increased from baseline 25% to 84% in patients. Δ SDI(exercise-baseline) correlated with exercise-baseline differences in LV ejection fraction (p<0.001) and stroke volume (p = 0.006). Compared with controls, patients had significantly less exercise-induced increase in LV ejection fraction, cardiac index, and IVA (interaction, all p<0.05) and had impaired contractile reserve as reflected by the gentler IVA-heart rate slope (p = 0.018). Cardiac T2* in patients correlated with baseline LV SDI (r = -0.44, p = 0.011) and IVA-heart rate slope (r = 0.36, p = 0.044).
CONCLUSIONS: Resting LV dyssynchrony is associated with myocardial iron load. Exercise stress further unveils LV dynamic dyssynchrony and impaired contractile reserve in patients with beta-thalassaemia major.
Yiu-fai Cheung; Wei Yu; Shu-na Li; Wendy W M Lam; Yuen-chi Ho; Sophia J Wong; Godfrey C F Chan; Shau-yin Ha
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-09-18
Journal Detail:
Title:  PloS one     Volume:  7     ISSN:  1932-6203     ISO Abbreviation:  PLoS ONE     Publication Date:  2012  
Date Detail:
Created Date:  2012-10-02     Completed Date:  2013-02-28     Revised Date:  2013-07-11    
Medline Journal Info:
Nlm Unique ID:  101285081     Medline TA:  PLoS One     Country:  United States    
Other Details:
Languages:  eng     Pagination:  e45265     Citation Subset:  IM    
Division of Paediatric Cardiology, Queen Mary Hospital, The University of Hong Kong, Hong Kong, China.
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MeSH Terms
Case-Control Studies
Echocardiography, Doppler
Exercise Test
Heart Ventricles / pathology,  physiopathology*,  ultrasonography
Iron / analysis
Magnetic Resonance Imaging
Myocardial Contraction
Myocardium / chemistry,  pathology*
Stroke Volume
Ventricular Dysfunction, Left / complications,  pathology,  physiopathology*,  ultrasonography
beta-Thalassemia / complications,  pathology,  physiopathology*,  ultrasonography
Reg. No./Substance:

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