Incremental value of radial discoordination index for the prediction of response to cardiac resynchronization therapy.

AIMS Previous studies have identified four baseline characteristics associated with a favourable response to cardiac resynchronization therapy (CRT): female, non-ischaemic aetiology of heart failure, left bundle-branch block (LBBB), and QRS duration ≥150 ms. This study evaluated the incremental value of discoordination and dyssynchrony indices over these characteristics for the prediction of the response to CRT. METHODS AND RESULTS The speckle-tracking strain analysis was performed in 120 CRT candidates. Patients were divided into subgroups according to the gender (male vs. female), aetiology of heart failure (ischaemic vs. non-ischaemic), QRS morphology (LBBB vs. non-LBBB), and QRS duration (≥150 vs. <150 ms), respectively. Discoordination was measured using the mid-ventricular radial discoordination index (RDI-M), the ratio of the average mid-ventricular thinning to thickening during ejection. Patients with one of the four favourable characteristics were more likely to exhibit other favourable characteristics and had greater amounts of average myocardial thinning during ejection and RDI-M than those without (all P< 0.05). In contrast, dyssynchrony indices failed to demonstrate significant differences between male and female and between ischaemic and non-ischaemic subjects. Of 39 patients who had 6-month follow-up data after CRT, left ventricular reverse remodelling was found in 22 patients (56%). Combining the favourable characteristics and RDI-M provides the best ability to predict reverse remodelling after CRT (area under the curve = 0.85, 95% confidence interval 0.73-0.98, P < 0.001). CONCLUSION Mechanical discoordination rather than mechanical dyssynchrony provides a significant incremental value over the baseline characteristics for the prediction of the response to CRT.