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Open Access Research article

QRS pattern and improvement in right and left ventricular function after cardiac resynchronization therapy: a radionuclide study

Giulia Domenichini12, Haran Burri2, Cinzia Valzania1, Gilberto Gavaruzzi3, Francesco Fallani1, Mauro Biffi1, Henri Sunthorn2, Igor Diemberger1, Cristian Martignani1, Huberdine Foulkes2, Eric Fleury2 and Giuseppe Boriani1*

Author Affiliations

1 Institute of Cardiology, University of Bologna, Via Massarenti 9, Bologna 40138, Italy

2 Cardiology Service, University Hospital of Geneva, Geneva, Switzerland

3 Department of Nuclear Medicine, S. Orsola-Malpighi Hospital, Bologna, Italy

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BMC Cardiovascular Disorders 2012, 12:27  doi:10.1186/1471-2261-12-27

Published: 11 April 2012

Abstract

Background

Predicting response to cardiac resynchronization therapy (CRT) remains a challenge. We evaluated the role of baseline QRS pattern to predict response in terms of improvement in biventricular ejection fraction (EF).

Methods

Consecutive patients (pts) undergoing CRT implantation underwent radionuclide angiography at baseline and at mid-term follow-up. The relationship between baseline QRS pattern and mechanical dyssynchrony using phase analysis was evaluated. Changes in left and right ventricular EF (LVEF and RVEF) were analyzed with regard to baseline QRS pattern.

Results

We enrolled 56 pts, 32 with left bundle branch block (LBBB), 4 with right bundle branch block (RBBB) and 20 with non-specific intraventricular conduction disturbance (IVCD). A total of 48 pts completed follow-up. LBBB pts had significantly greater improvement in LVEF compared to RBBB or non-specific IVCD pts (+9.6 ± 10.9% vs. +2.6 ± 7.6%, p = 0.003). Response (defined as ≥ 5% increase in LVEF) was observed in 68% of LBBB vs. 24% of non-specific IVCD pts (p = 0.006). None of the RBBB pts were responders. RVEF was significantly improved in LBBB (+5.0 ± 9.0%, p = 0.007), but not in non-specific IVCD and RBBB pts (+0.4 ± 5.8%, p = 0.76). At multivariate analysis, LBBB was the only predictor of LVEF response (OR, 7.45; 95% CI 1.80-30.94; p = 0.006), but not QRS duration or extent of mechanical dyssynchrony.

Conclusions

Presence of a LBBB is a marker of a positive response to CRT in terms of biventricular improvement. Pts with non-LBBB pattern show significantly less benefit from CRT than those with LBBB.

Keywords:
Cardiac resynchronization therapy; Left ventricular ejection fraction; Right ventricular ejection fraction; Dyssynchrony; Nuclear angiography; QRS morphology