Dyssynchrony by speckle-tracking echocardiography and response to cardiac resynchronization therapy: results of the Speckle Tracking and Resynchronization (STAR) study

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) < or =35%, and QRS > or =120 ms from three international centres. Baseline dyssynchrony was evaluated by four speckle tracking strain methods; radial, circumferential, transverse, and longitudinal (> or =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.

Figures

Figure 1

An example of speckle-tracking dyssynchrony analysis from mid-ventricular short-axis views demonstrating radial (A) and circumferential (B) time–strain curves in a heart failure patient with left bundle-branch block. Dyssynchrony is shown as a time difference (arrow) between time to peak strain in the anterior septum (orange curve) and posterior wall peak strain (green curve). ECG, electrocardiogram; Ant-sep, anterior septum.

Figure 2

An example of speckle-tracking dyssynchrony analysis from an apical four-chamber view demonstrating transverse (A) and longitudinal (B) time–strain curves in a heart failure patient with left bundle-branch block. Dyssynchrony is shown as a maximum opposing wall delay (arrow) in time-to-peak strain among three apical views; four-chamber, two-chamber, and long-axis. ECG, electrocardiogram.

Figure 3

Feasibility of speckle-tracking dyssynchrony analysis in consecutive patients with attempted echocardiograms. CRT, cardiac resynchronization therapy; LV, left ventricular.

Figure 4

Bar graphs of ejection fraction (EF) values before and 7 ± 4 months after cardiac resynchronization therapy (CRT) in patients with and without significant radial and transverse dyssynchrony. Both radial and transverse dyssynchrony were associated with significant improvement in EF after CRT.

Figure 5

Receiver operating characteristics curve analysis of speckle-tracking strain approaches to dyssynchrony for predicting outcome after cardiac resynchronization therapy. (A) Ejection fraction (EF) response ≥15% and (B) event-free survival (freedom from death, transplant, or left ventricular assist device). Radial and transverse strain dyssynchrony were successfully predictive of response to CRT; however, circumferential and longitudinal strains were not. The combination of radial and transverse dyssynchrony was the most predictive of EF response and long-term outcome following CRT.

Figure 6

Kaplan–Meier curves of probability of freedom from death, transplant, or left ventricular assist device after cardiac resynchronization therapy (CRT). Baseline radial and transverse dyssynchrony ≥130 ms were associated with a significantly more favourable outcome.

Figure 7

Kaplan–Meier curves of probability of freedom from death, transplant, or left ventricular assist device after cardiac resynchronization therapy (CRT). Neither circumferential nor longitudinal dyssynchrony was associated with outcome.

Figure 8

Bar graph of per cent of patients with serious unfavourable events of death, heart transplant, or left ventricular assist device (LVAD) after cardiac resynchronization therapy. Patients with dyssynchrony identified by all speckle-tracking strain approaches had a low adverse event rate. Patients who had dyssynchrony excluded by radial or transverse strain had a significantly higher per cent of unfavourable events, in particular when combined.