title: Strain dyssynchrony index determined by three-dimensional speckle area tracking can predict response to cardiac resynchronization therapy.
abstract: BACKGROUND
  We have previously reported strain dyssynchrony index assessed by two-dimensional speckle tracking strain, and a marker of both dyssynchrony and residual myocardial contractility, can predict response to cardiac resynchronization therapy (CRT). A newly developed three-dimensional (3-D) speckle tracking system can quantify endocardial area change ratio (area strain), which coupled with the factors of both longitudinal and circumferential strain, from all 16 standard left ventricular (LV) segments using complete 3-D pyramidal datasets. Our objective was to test the hypothesis that strain dyssynchrony index using area tracking (ASDI) can quantify dyssynchrony and predict response to CRT.
  
  
  METHODS
  We studied 14 heart failure patients with ejection fraction of 27 ± 7% (all≤35%) and QRS duration of 172 ± 30 ms (all≥120 ms) who underwent CRT. Echocardiography was performed before and 6-month after CRT. ASDI was calculated as the average difference between peak and end-systolic area strain of LV endocardium obtained from 3-D speckle tracking imaging using 16 segments. Conventional dyssynchrony measures were assessed by interventricular mechanical delay, Yu Index, and two-dimensional radial dyssynchrony by speckle-tracking strain. Response was defined as a ≥15% decrease in LV end-systolic volume 6-month after CRT.
  
  
  RESULTS
  ASDI ≥ 3.8% was the best predictor of response to CRT with a sensitivity of 78%, specificity of 100% and area under the curve (AUC) of 0.93 (p < 0.001). Two-dimensional radial dyssynchrony determined by speckle-tracking strain was also predictive of response to CRT with an AUC of 0.82 (p < 0.005). Interestingly, ASDI ≥ 3.8% was associated with the highest incidence of echocardiographic improvement after CRT with a response rate of 100% (7/7), and baseline ASDI correlated with reduction of LV end-systolic volume following CRT (r = 0.80, p < 0.001).
  
  
  CONCLUSIONS
  ASDI can predict responders and LV reverse remodeling following CRT. This novel index using the 3-D speckle tracking system, which shows circumferential and longitudinal LV dyssynchrony and residual endocardial contractility, may thus have clinical significance for CRT patients.
authors.affiliation: Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Tatsumi
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Tanaka
authors.forename: Takayuki
authors.initials: T
authors.lastname: Tsuji
authors.forename: Akihiro
authors.initials: A
authors.lastname: Kaneko
authors.forename: Keiko
authors.initials: K
authors.lastname: Ryo
authors.forename: Kohei
authors.initials: K
authors.lastname: Yamawaki
authors.forename: Alaa M S
authors.initials: AM
authors.lastname: Omar
authors.forename: Yuko
authors.initials: Y
authors.lastname: Fukuda
authors.forename: Kazuko
authors.initials: K
authors.lastname: Norisada
authors.forename: Kensuke
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Tetsuari
authors.initials: T
authors.lastname: Onishi
authors.forename: Akihiro
authors.initials: A
authors.lastname: Yoshida
authors.forename: Hiroya
authors.initials: H
authors.lastname: Kawai
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Hirata
mesh_terms: D000368:Aged; D019540:Area Under Curve; D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging* / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D010138:Pacemaker, Artificial; D011237:Predictive Value of Tests; D011379:Prognosis; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013318:Stroke Volume; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000503:physiopathology* / Q000628:therapy*