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Article: Dynamic dyssynchrony and impaired contractile reserve of the left ventricle in beta-thalassaemia major: an exercise echocardiographic study

TitleDynamic dyssynchrony and impaired contractile reserve of the left ventricle in beta-thalassaemia major: an exercise echocardiographic study
Authors
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
Citation
PLoS One, 2012, v. 7 n. 9, article no. e45265 How to Cite?
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<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.
Persistent Identifierhttp://hdl.handle.net/10722/169221
ISSN
2013 Impact Factor: 3.534
2013 SCImago Journal Rankings: 1.724
PubMed Central ID
ISI Accession Number ID

 

Author Affiliations
  1. The University of Hong Kong
DC FieldValueLanguage
dc.contributor.authorCheung, YFen_US
dc.contributor.authorYu, Wen_US
dc.contributor.authorLi, SNen_US
dc.contributor.authorLam, WWMen_US
dc.contributor.authorHo, YCen_US
dc.contributor.authorWong, SJen_US
dc.contributor.authorChan, GCFen_US
dc.contributor.authorHa, SYen_US
dc.date.accessioned2012-10-18T08:46:00Z-
dc.date.available2012-10-18T08:46:00Z-
dc.date.issued2012en_US
dc.identifier.citationPLoS One, 2012, v. 7 n. 9, article no. e45265en_US
dc.identifier.issn1932-6203-
dc.identifier.urihttp://hdl.handle.net/10722/169221-
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.languageengen_US
dc.publisherPublic Library of Science. The Journal's web site is located at http://www.plosone.org/home.action-
dc.relation.ispartofPLoS Oneen_US
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 studyen_US
dc.typeArticleen_US
dc.identifier.emailCheung, YF: xfcheung@hku.hken_US
dc.identifier.emailWong, SJ: sjwong@hku.hken_US
dc.identifier.emailChan, GCF: gcfchan@hku.hken_US
dc.identifier.emailHa, SY: syha@hku.hken_US
dc.identifier.authorityCheung, YF=rp00382en_US
dc.identifier.authorityChan, GCF=rp00431en_US
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.1371/journal.pone.0045265-
dc.identifier.pmid23028894-
dc.identifier.pmcidPMC3445473-
dc.identifier.scopuseid_2-s2.0-84866481285-
dc.identifier.hkuros212090en_US
dc.identifier.volume7en_US
dc.identifier.issue9, article no. e45265-
dc.identifier.isiWOS:000311313900109-
dc.publisher.placeUnited States-

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