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Circ J. 2011;75(9):2167-75. Epub 2011 Jul 14.

Novel strain rate index of contractility loss caused by mechanical dyssynchrony. - A predictor of response to cardiac resynchronization therapy-.

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1
Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan.

Abstract

BACKGROUND:

Time-delay indexes are limited in predicting the response to cardiac resynchronization therapy (CRT), partly because they do not reflect the residual left ventricular (LV) contractility. We computed a novel index of LV contractility loss due to dyssynchrony (the strain rate (SR) dispersion index: SRDI) by using the speckle-tracking SR and compared the efficacy of the SRDI, time-delay indexes, and strain delay index (SDI), the previously reported index of wasted energy due to dyssynchrony, for predicting the acute response to CRT.

METHODS AND RESULTS:

Echocardiography was performed in 19 heart failure patients (LV ejection fraction (EF) 25 ± 6%) before and 2 weeks after CRT. The standard deviation of time to peak velocity, or strain, was calculated as time-delay indexes. The SRDI was calculated as the average of segmental peak systolic SR minus global peak systolic SR. Longitudinal SDI (L-SDI), longitudinal SRDI (L-SRDI), and circumferential SRDI (C-SRDI) significantly correlated with the change in global longitudinal strain (Δglobal LSt), whereas the time-delay indexes did not. Although the time-delay indexes were comparable between responders (Δglobal LSt ≥ 0.3%) and nonresponders, the L-SDI, L-SRDI, and C-SRDI were greater in responders. The area under the receiver operating characteristic curve of the L-SRDI, L-SDI, and C-SRDI for predicting responders was 0.89, 0.81, and 0.78, respectively.

CONCLUSIONS:

The SRDI correlated fairly well with an improvement in global LV systolic function after CRT.

PMID:
21757822
[Indexed for MEDLINE]
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