Effects of global longitudinal strain and total scar burden on response to cardiac resynchronization therapy in patients with ischaemic dilated cardiomyopathy

Aims To evaluate whether quantification of the extent of scarred left ventricular (LV) tissue by speckle‐tracking strain echo (2DSE) can predict response to cardiac resynchronization therapy (CRT) in patients with ischaemic dilated cardiomyopathy (DCM). Methods and results Forty‐five patients (58.3 ± 8.3 years; 24 males) with ischaemic DCM scheduled for CRT, and 25 controls were studied. A week before implantation all the patients underwent standard Doppler echo, 2DSE, and contrast‐enhanced magnetic resonance (MR). Clinical and echocardiographic evaluation was repeated 6 months after CRT. The patients were considered as responders to CRT if LV end‐systolic volume decreased by 15%. In DCM patients, LV ejection fraction was 29.2 ± 5.1%. By evaluating the 765 segments with MR, subendocardial infarct was identified in 17.0% and transmural infarct in 18.3%. With 2DSE, the average global longitudinal strain (GLS) was −23.1 ± 3.6% in controls and −15.1 ± 5.1% in DCM ( P = 0.001). GLS showed a close correlation with total scar burden using MR ( r = 0.64, P < 0.001). At follow‐up, patients were subdivided into responders ( n = 30; 66.7%) and non‐responders ( n = 15; 33.3%) to CRT. GLS was significantly different in non‐responders than in responders (GLS: −10.4 ± 5.1 in non‐responders vs. −18.4 ± 14% in responders, P < 0.001). In a multivariable analysis, GLS ( P < 0.0001) and radial intraventricular dyssynchrony ( P < 0.001) were powerful independent determinants of response to CRT. Conclusion GLS is strongly associated with total scar burden assessed by MR, and is an excellent independent predictor of response to CRT.