Response to Cardiac Resynchronization Therapy as Assessed by Time-Based Speckle Tracking Imaging

BackgroundResponse to cardiac resynchronization therapy (CRT) is still difficult to predict with previously investigated dyssynchrony indices. The predictive value of speckle tracking strain analysis has not been fully delineated yet. The objective of this study was to assess the predictive value of longitudinal strain (LS) and radial strain (RS) speckle tracking measurements on echocardiographic and clinical response to CRT. MethodsA total of 138 consecutive patients with functional class II-IV heart failure who underwent CRT were studied. Echocardiography was performed at baseline and during follow-up. Six different time-based left ventricular (LV)-dyssynchrony indices were measured with LS and RS. Echocardiographic response to CRT was defined as a reduction in LV end-systolic volume 15% and clinical response as survival without heart failure hospitalization. Multivariable analyses were performed to adjust for potential confounding factors. ResultsEchocardiographic and clinical follow-up was 22 8 and 42 +/- 8 months, respectively. Ninety-six patients (70%) were classified as echocardiographic responders and 114 patients (83%) survived without heart failure hospitalization. QRS duration and nonischemic etiology predicted echocardiographic response to CRT. None of the speckle tracking indices was different between echocardiographic responders and nonresponders to CRT. Regarding clinical response, only maximal delay between six segments in four-chamber view measured with LS was different between responders and nonresponders, with 154-ms delay as the optimal cut-off value. Neither stratified analyses in patients with sinus rhythm nor multivariable analyses did change these findings. ConclusionOf all time-based measured speckle tracking indices, only maximal delay between six segments in four-chamber view as assessed with LS was associated with clinical response to CRT.