Multicentre study using strain delay index for predicting response to cardiac resynchronization therapy (MUSIC study)

Aims Strain delay index (SDI) allows quantification of the wasted contraction or gain of myocardial contractility expected after cardiac resynchronization therapy (CRT). The present multicentre prospective study aimed to assess the accuracy of the SDI in predicting responses to CRT in real‐life patients with wide and narrow (15%. After CRT, ESVR>15% was observed in 60% (n= 114/189) of patients, and was greater in non‐ischaemic (68 vs. 44%, P= 0.003) and wide QRS patients (65 vs. 49%, P= 0.04). Correlation between 12SD‐ɛ and ESVR was poor (r = 0.18, P= 0.01). In contrast, SDI correlated with reverse remodelling (r = 0.61, P< 0.0001 for all) in both wide and narrow QRS patients and ischaemic and non‐ischaemic patients. Decrease in SDI after CRT was greater in responders and correlated with ESVR. Finally, SDI > 25% identified responders to CRT (positive and negative predictive value of 80 and 84%, respectively) with 6% inter‐observer variability. Conclusion The present multicentre study suggests that SDI may identify responders to CRT in ischaemic and non‐ischaemic patients.