Dyssynchrony by Speckle-tracking Echo and Response to CRT
Dyssynchrony by Speckle-tracking Echo and Response to CRT
Aims The Speckle Tracking and Resynchronization (STAR) study used a prospective multi-centre design to test the hypothesis that speckle-tracking echocardiography can predict response to cardiac resynchronization therapy (CRT).
Methods and results We studied 132 consecutive CRT patients with class III and IV heart failure, ejection fraction (EF) ≤35%, and QRS ≥120 ms from three international centres. Baseline dyssynchrony was evaluated by four speckle tracking strain methods; radial, circumferential, transverse, and longitudinal (≥130 ms opposing wall delay for each). Pre-specified outcome variables were EF response and three serious long-term events: death, transplant, or left ventricular assist device. Of 120 patients (91%) with baseline dyssynchrony data, both short-axis radial strain and transverse strain from apical views were associated with favourable EF response 7 ± 4 months and long-term outcome over 3.5 years (P < 0.01). Radial strain had the highest sensitivity at 86% for predicting EF response with a specificity of 67%. Serious long-term unfavourable events occurred in 20 patients after CRT, and happened three times more frequently in those who lacked baseline radial or transverse dyssynchrony than in patients with dyssynchrony (P < 0.01). Patients who lacked both radial and transverse dyssynchrony had unfavourable clinical events occur in 53%, in contrast to events occurring in 12% if baseline dyssynchrony was present (P < 0.01). Circumferential and longitudinal strains predicted response when dyssynchrony was detected, but failed to identify dyssynchrony in one-third of patients who responded to CRT.
Conclusion Dyssynchrony by speckle-tracking echocardiography using radial and transverse strains is associated with EF response and long-term outcome following CRT.
Cardiac resynchronization therapy (CRT) is an established therapy for selected heart failure (HF) patients. Current selection criteria for CRT include patients with New York Heart Association functional class III or IV on optimal pharmacologic therapy, QRS ≥ 120 ms, and ejection fraction (EF) ≤35%. Because significant subgroups of patients do not experience benefits of CRT, such as improved symptoms, ventricular function, or survival, echocardiographic techniques have been of interest to quantify LV mechanical dyssynchrony as a means to predict patient response. However, the PROSPECT (predictors of responders to cardiac resynchronization therapy) study suggested that echocardiographic dyssynchrony, such as tissue Doppler, did not have enough predictive value to replace routine selection criteria for CRT. Speckle-tracking echocardiography is a more recent approach that allows for strain imaging to assess dyssynchrony. Four different types of speckle-tracking approaches have been described included radial strain (myocardial thickening) and circumferential strain (myocardial shortening) assessed from short-axis views; and transverse (myocardial thickening) and longitudinal strains (myocardial shortening) assessed from apical views. Our objectives were to test the hypothesis that speckle-tracking strain can quantify dyssynchrony and predict response to CRT in a prospective, multicentre, long-term study and to elucidate which of the above speckle-tracking strain approaches were most closely associated with outcome.
Abstract and Introduction
Abstract
Aims The Speckle Tracking and Resynchronization (STAR) study used a prospective multi-centre design to test the hypothesis that speckle-tracking echocardiography can predict response to cardiac resynchronization therapy (CRT).
Methods and results We studied 132 consecutive CRT patients with class III and IV heart failure, ejection fraction (EF) ≤35%, and QRS ≥120 ms from three international centres. Baseline dyssynchrony was evaluated by four speckle tracking strain methods; radial, circumferential, transverse, and longitudinal (≥130 ms opposing wall delay for each). Pre-specified outcome variables were EF response and three serious long-term events: death, transplant, or left ventricular assist device. Of 120 patients (91%) with baseline dyssynchrony data, both short-axis radial strain and transverse strain from apical views were associated with favourable EF response 7 ± 4 months and long-term outcome over 3.5 years (P < 0.01). Radial strain had the highest sensitivity at 86% for predicting EF response with a specificity of 67%. Serious long-term unfavourable events occurred in 20 patients after CRT, and happened three times more frequently in those who lacked baseline radial or transverse dyssynchrony than in patients with dyssynchrony (P < 0.01). Patients who lacked both radial and transverse dyssynchrony had unfavourable clinical events occur in 53%, in contrast to events occurring in 12% if baseline dyssynchrony was present (P < 0.01). Circumferential and longitudinal strains predicted response when dyssynchrony was detected, but failed to identify dyssynchrony in one-third of patients who responded to CRT.
Conclusion Dyssynchrony by speckle-tracking echocardiography using radial and transverse strains is associated with EF response and long-term outcome following CRT.
Introduction
Cardiac resynchronization therapy (CRT) is an established therapy for selected heart failure (HF) patients. Current selection criteria for CRT include patients with New York Heart Association functional class III or IV on optimal pharmacologic therapy, QRS ≥ 120 ms, and ejection fraction (EF) ≤35%. Because significant subgroups of patients do not experience benefits of CRT, such as improved symptoms, ventricular function, or survival, echocardiographic techniques have been of interest to quantify LV mechanical dyssynchrony as a means to predict patient response. However, the PROSPECT (predictors of responders to cardiac resynchronization therapy) study suggested that echocardiographic dyssynchrony, such as tissue Doppler, did not have enough predictive value to replace routine selection criteria for CRT. Speckle-tracking echocardiography is a more recent approach that allows for strain imaging to assess dyssynchrony. Four different types of speckle-tracking approaches have been described included radial strain (myocardial thickening) and circumferential strain (myocardial shortening) assessed from short-axis views; and transverse (myocardial thickening) and longitudinal strains (myocardial shortening) assessed from apical views. Our objectives were to test the hypothesis that speckle-tracking strain can quantify dyssynchrony and predict response to CRT in a prospective, multicentre, long-term study and to elucidate which of the above speckle-tracking strain approaches were most closely associated with outcome.