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

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Publisher Website: 10.1371/journal.pone.0045265
Scopus: eid_2-s2.0-84866481285
PMID: 23028894

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Title	Dynamic dyssynchrony and impaired contractile reserve of the left ventricle in beta-thalassaemia major: an exercise echocardiographic study
Authors	Cheung, YF1 Yu, W1 Li, SN1 Lam, WWM1 Ho, YC1 Wong, SJ1 Chan, GCF1 Ha, SY1
Keywords	Bicycle Cardiovascular magnetic resonance Cardiovascular parameters Controlled study Correlation analysis
Issue Date	2012
Publisher	Public 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?] DOI: http://dx.doi.org/10.1371/journal.pone.0045265
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.
ISSN	1932-6203 2011 Impact Factor: 4.092 2011 SCImago Journal Rankings: 0.519
DOI	http://dx.doi.org/10.1371/journal.pone.0045265
PubMed Central ID	PMC3445473

DC Field	Value
dc.contributor.author	Cheung, YF
dc.contributor.author	Yu, W
dc.contributor.author	Li, SN
dc.contributor.author	Lam, WWM
dc.contributor.author	Ho, YC
dc.contributor.author	Wong, SJ
dc.contributor.author	Chan, GCF
dc.contributor.author	Ha, SY
dc.date.accessioned	2012-10-18T08:46:00Z
dc.date.available	2012-10-18T08:46:00Z
dc.date.issued	2012
dc.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<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.nature	published_or_final_version
dc.identifier.citation	PLoS One, 2012, v. 7 n. 9, article no. e45265 [How to Cite?] DOI: http://dx.doi.org/10.1371/journal.pone.0045265
dc.identifier.doi	http://dx.doi.org/10.1371/journal.pone.0045265
dc.identifier.hkuros	212090
dc.identifier.issn	1932-6203 2011 Impact Factor: 4.092 2011 SCImago Journal Rankings: 0.519
dc.identifier.issue	9, article no. e45265
dc.identifier.pmcid	PMC3445473
dc.identifier.pmid	23028894
dc.identifier.scopus	eid_2-s2.0-84866481285
dc.identifier.uri	http://hdl.handle.net/10722/169221
dc.identifier.volume	7
dc.language	eng
dc.publisher	Public Library of Science. The Journal's web site is located at http://www.plosone.org/home.action
dc.publisher.place	United States
dc.relation.ispartof	PLoS One
dc.rights	Creative Commons: Attribution 3.0 Hong Kong License
dc.subject	Bicycle
dc.subject	Cardiovascular magnetic resonance
dc.subject	Cardiovascular parameters
dc.subject	Controlled study
dc.subject	Correlation analysis
dc.title	Dynamic dyssynchrony and impaired contractile reserve of the left ventricle in beta-thalassaemia major: an exercise echocardiographic study
dc.type	Article

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Author Affiliations

The University of Hong Kong