title: 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 patients with heart failure were referred for cardiac resynchronization therapy (CRT) with an ejection fraction 25 +/- 6% and QRS interval 165 +/- 29 ms and 10 healthy volunteer controls. The 3-D speckle tracking system determined radial strain using a 16-segment model from a pyramidal 3-D dataset. Dyssynchrony was quantified as maximal opposing wall delay and SD in time to peak strain. The 3-D analysis was compared to standard 2-dimensional (2-D) strain datasets and site of 3-D latest mechanical activation, not possible by 2D was quantified. As expected, dyssynchrony in patients on CRT was significantly greater than in controls (maximal opposing wall delay 316 +/- 112 vs 59 +/- 12 ms and SD 124 +/- 48 vs 28 +/- 11 ms, p <0.001 vs normal). The 3-D opposing wall delay was closely correlated with 3-D 16-segment SD (r = 0.95) and 2-D mid-LV strain (r = 0.83) and SD (r = 0.85, all p values <0.001). The 3-D site of the latest mechanical activation was most commonly midposterior (26%), basal posterior (22%), midlateral (20%), and basal lateral (17%). Eleven patients studied after CRT demonstrated improvements in 3-D synchrony (300 +/- 124 to 94 +/- 37 ms) and ejection fraction (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 patients on CRT.
authors.affiliation: University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Tanaka
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Hara
authors.forename: Samir
authors.initials: S
authors.lastname: Saba
authors.forename: John
authors.initials: J
authors.lastname: Gorcsan
mesh_terms: D000328:Adult; D000368:Aged; D002304:Cardiac Pacing, Artificial; D019560:Echocardiography, Three-Dimensional / Q000379:methods*; D005260:Female; D006333:Heart Failure / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology; D011237:Predictive Value of Tests; D012307:Risk Factors; D013314:Stress, Mechanical; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000209:etiology / Q000628:therapy*