Multicentre Study Using Strain Delay Index for Predicting Response to Cardiac Resynchronization Therapy (MUSIC study)

189 heart failure patients undergoing cardiac resynchronization therapy (CRT) implantation with analysable echocardiography data (from an initial cohort of 235), mean age 65 ± 12 years, LVEF 26 ± 8%, 63 with ischaemic aetiology, 51 with narrow QRS complexes (<130 ms).

Strain Delay Index (SDI) measurement by echocardiography (speckle tracking) to quantify mechanical dyssynchrony

12-segment standard deviation of peak longitudinal strain by speckle tracking (12SD-ε)

Response to CRT, defined as an end-systolic volume reduction (ESVR) >15% at 6 monthssurrogate