Usefulness of Three-Dimensional Speckle Tracking Strain to Quantify Dyssynchrony and the Site of Latest Mechanical Activation

Abstract

Previous methods to quantify dyssynchrony could not determine regional 3-dimensional (3-D)strain. We hypothesized that a novel 3-D speckle tracking strain imaging system can quantify left ventricular (LV) dyssynchrony and site of latest mechanical activation. We studied 64 subjects; 54 heart failure patients referred for cardiac resynchronization therapy (CRT) with ejection fraction 25±6% and QRS 165±29ms and 10 normal controls. The 3-D speckle tracking system determined radial strain using a 16-segment model from a pyramidal 3-D data set. Dyssynchrony was quantified as maximal opposing wall delay and standard deviation in time-to-peak strain. 3-D analysis was compared with standard 2-dimensional (2-D) strain data sets and site of 3-D latest mechanical activation, not possible by 2D was quantified. As expected, dyssynchrony in CRT patients was significantly greater than normal controls (maximal opposing wall delay 316±112* ms vs. 59±12 ms and standard deviation 124±48* ms vs. 28±11 ms, *p<0.001 vs. normal). 3-D opposing wall delay was closely correlated with 3-D 16-segment standard deviation (r = 0.95), and 2-D mid-LV strain: r=0.83 and r=0.85 for standard deviation (all p<0.001). The 3-D site of the latest mechanical activation was most commonly mid-posterior (26%), basal-posterior (22%), mid-lateral (20%), and basal-lateral (17%). Eleven patients studied after CRT demonstrated improvements in 3D synchrony (300±124 ms to 94±37 ms*) and EF (24 ± 6% to 31 ± 7%*), *p<0.05. In conclusion, 3-D speckle tracking can successfully quantify 3-D dyssynchrony and site the latest mechanical activation. This approach may play a clinical role in management of CRT patients. Keywordsechocardiography; heart failure; pacemakers Cardiac resynchronization therapy (CRT) has had a major impact on improving symptoms and survival in heart failure (HF) patients. A large body of data has demonstrated that abnormalities of left ventricular (LV) mechanical timing, known as dyssynchrony, impairs ejection efficiency and is improved with CRT. 1-3 Existing echocardiographic methods to quantify dyssynchrony, such as tissue Doppler, have been shown to have technical limitations which preclude their routine use for patient selection for CRT.4 -7. Accordingly, there is a desire for technological © 2009 Excerpta Medica, Inc. Published by Elsevier Inc. All rights reserved.Corresponding author: John Gorcsan III, MD, University of Pittsburgh, Scaife Hall 564, 200 Lothrop Street, Pittsburgh, PA 15213-2582, Phone: 412-647-6570, Fax: 412-647-0568, gorcsanj@upmc.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal ...

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Finding Pieces of the Puzzle of Nonresponse to Cardiac Resynchronization Therapy

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