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Article: Dynamic dyssynchrony and impaired contractile reserve of the left ventricle in beta-thalassaemia major: an exercise echocardiographic study
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TitleDynamic dyssynchrony and impaired contractile reserve of the left ventricle in beta-thalassaemia major: an exercise echocardiographic study
 
AuthorsCheung, YF1
Yu, W1
Li, SN1
Lam, WWM1
Ho, YC1
Wong, SJ1
Chan, GCF1
Ha, SY1
 
KeywordsBicycle
Cardiovascular magnetic resonance
Cardiovascular parameters
Controlled study
Correlation analysis
 
Issue Date2012
 
PublisherPublic Library of Science. The Journal's web site is located at http://www.plosone.org/home.action
 
CitationPLoS One, 2012, v. 7 n. 9, article no. e45265 [How to Cite?]
DOI: http://dx.doi.org/10.1371/journal.pone.0045265
 
AbstractBACKGROUND: 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. Delta 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.
 
ISSN1932-6203
2013 Impact Factor: 3.534
2013 SCImago Journal Rankings: 1.724
 
DOIhttp://dx.doi.org/10.1371/journal.pone.0045265
 
PubMed Central IDPMC3445473
 
DC FieldValue
dc.contributor.authorCheung, YF
 
dc.contributor.authorYu, W
 
dc.contributor.authorLi, SN
 
dc.contributor.authorLam, WWM
 
dc.contributor.authorHo, YC
 
dc.contributor.authorWong, SJ
 
dc.contributor.authorChan, GCF
 
dc.contributor.authorHa, SY
 
dc.date.accessioned2012-10-18T08:46:00Z
 
dc.date.available2012-10-18T08:46:00Z
 
dc.date.issued2012
 
dc.description.abstractBACKGROUND: 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. Delta 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.
 
dc.description.naturepublished_or_final_version
 
dc.identifier.citationPLoS One, 2012, v. 7 n. 9, article no. e45265 [How to Cite?]
DOI: http://dx.doi.org/10.1371/journal.pone.0045265
 
dc.identifier.doihttp://dx.doi.org/10.1371/journal.pone.0045265
 
dc.identifier.hkuros212090
 
dc.identifier.issn1932-6203
2013 Impact Factor: 3.534
2013 SCImago Journal Rankings: 1.724
 
dc.identifier.issue9, article no. e45265
 
dc.identifier.pmcidPMC3445473
 
dc.identifier.pmid23028894
 
dc.identifier.scopuseid_2-s2.0-84866481285
 
dc.identifier.urihttp://hdl.handle.net/10722/169221
 
dc.identifier.volume7
 
dc.languageeng
 
dc.publisherPublic Library of Science. The Journal's web site is located at http://www.plosone.org/home.action
 
dc.publisher.placeUnited States
 
dc.relation.ispartofPLoS One
 
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License
 
dc.subjectBicycle
 
dc.subjectCardiovascular magnetic resonance
 
dc.subjectCardiovascular parameters
 
dc.subjectControlled study
 
dc.subjectCorrelation analysis
 
dc.titleDynamic dyssynchrony and impaired contractile reserve of the left ventricle in beta-thalassaemia major: an exercise echocardiographic study
 
dc.typeArticle
 
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<item><contributor.author>Cheung, YF</contributor.author>
<contributor.author>Yu, W</contributor.author>
<contributor.author>Li, SN</contributor.author>
<contributor.author>Lam, WWM</contributor.author>
<contributor.author>Ho, YC</contributor.author>
<contributor.author>Wong, SJ</contributor.author>
<contributor.author>Chan, GCF</contributor.author>
<contributor.author>Ha, SY</contributor.author>
<date.accessioned>2012-10-18T08:46:00Z</date.accessioned>
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<date.issued>2012</date.issued>
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<identifier.issn>1932-6203</identifier.issn>
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<description.abstract>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&lt;0.001) but similar IVA (p = 0.22) compared with controls. With exercise stress, the prevalence of mechanical dyssynchrony (SDI&gt;4.6%, control+2SD) increased from baseline 25% to 84% in patients. Delta SDI(exercise-baseline) correlated with exercise-baseline differences in LV ejection fraction (p&lt;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&lt;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.</description.abstract>
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<subject>Bicycle</subject>
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Author Affiliations
  1. The University of Hong Kong