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Updated: Jul 9, 2026

Evaluation of Left Ventricular Structure and Function using 3D Echocardiography
Published on: October 28, 2020
Assessment of left ventricular dyssynchrony in patients with heart failure and normal QRS duration
Vidya Narayan1, Padmini Varadarajan, Ramdas G Pai
1Division of Cardiology, University of Southern California-Keck School of Medicine, Los Angeles, CA, USA.
Abstract:
Cardiac resynchronization therapy (CRT) is an important component of heart failure therapy in patients with a left ventricular ejection fraction <35%, class III or ambulatory class IV symptoms, and a QRS duration >120 ms. The QRS duration criterion for patient selection is imperfect. About 30% of patients with an increased QRS duration are nonresponders to CRT and many with a normal QRS duration with mechanical dyssynchrony respond to CRT. The authors review the currently available echocardiographic tools for the assessment of ventricular dyssynchrony in patients with heart failure.
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