Evaluation of global left ventricular function and mechanical dyssynchrony in patients with an asymptomatic left bundle branch block: a real-time 3D echocardiography study
1 Department of Cardiology ZH 6D 120, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands
2 Interuniversity Cardiology Institute of the Netherlands (ICIN), Utrecht, The Netherlands
3 Department of Clinical Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands
Received 14 November 2006; accepted after revision 4 March 2007; online publish-ahead-of-print 24 April 2007.
* Corresponding author. Tel: +31 20 444 2244; fax: +31 20 444 2446. E-mail address: jeroen.vandijk{at}vumc.nl
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Abstract |
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Background: A left bundle branch block (LBBB) affects both global left ventricular (LV) function and mechanical dyssynchrony. The aim was to evaluate global LV function and mechanical dyssynchrony with real-time 3D echocardiography (RT3DE), in asymptomatic LBBB patients, healthy volunteers and patients with symptomatic heart failure (HF) and a LBBB. Furthermore, the relation between presence or absence of symptoms of HF and mechanical dyssynchrony was investigated.
Methods: RT3DE was performed in 61 consecutive patients: 16 healthy volunteers, 22 patients with an asymptomatic LBBB and 23 patients with symptomatic HF and a LBBB. Global LV function and the systolic dyssynchrony index (SDI) were measured.
Results: In healthy volunteers, mean LV ejection fraction was 54 ± 5%, in asymptomatic LBBB patients 50 ± 9%, and in HF patients 29 ± 9%. SDI was 5.6 ± 3.6%, 7.3 ± 3.2% and 12.8 ± 4.8% for healthy volunteers, asymptomatic LBBB patients and HF patients respectively. SDI differed significantly between HF patients and both other groups. A cut-off value for SDI for presence of symptoms of HF was 10.8%.
Conclusion: Asymptomatic LBBB patients have more depressed global LV function than healthy volunteers have; patients with symptoms of HF and a LBBB have severe global LV dysfunction. Asymptomatic LBBB patients have an intermediate mechanical dyssynchrony; HF patients with a LBBB have the most severe mechanical dyssynchrony. A substantial amount of mechanical dyssynchrony might be accompanied by the presence of symptoms of HF.
Keywords: 3D echocardiography; Left bundle branch block; Heart failure; Healthy volunteers