Aim. To assess a relationship of left bundle branch block (LBBB) patterns defined by electrocardiography (ECG) and echocardiography with super-response (SR) to cardiac resynchronization therapy (CRT).Material and methods. Sixty patients (mean age, 54,5±10,4 years) were examined at baseline and during follow-up (10,6±3,6 months). Patients were divided into groups: group I (n=31) — decrease of left ventricular end-systolic volume (ESV) ≥30% (super-responders) and II group (n=29) — decrease of LV ESV <30% (non-super-responders). Three strain-markers of LBBB assessed by tissue Doppler imaging (TDI) and speckle tracking echocardiography (STE) were used: early contraction of basal or midventricular segment in the septal wall and early stretching of basal or midventricular segment in the lateral wall (marker 1); early peak contraction of the septal wall occurred in the first 70% of the systolic ejection phase (marker 2, septal flash (SF)); early stretching wall that showed peak contraction after aortic valve closure (marker 3). The classical LBBB pattern was defined if all three strain-markers were present. The heterogeneous LBBB pattern was defined if two from three strain-markers were present.Results. At baseline, groups did not differ in main clinical characteristics, including QRS width and LBBB assessed by ECG. Mechanical abnormalities were found only in group I: SF (32,3% vs 0,0%; p=0,001) and apical rocking (19,4% vs 0,0%; p=0,024), as well as classic LBBB mechanical pattern (20,8% vs 0,0%; p=0,05). The complex of heterogeneous LBBB mechanical pattern (odds ratio (OR), 7,512; 95% CI, 1,434-39,632; р=0,025), interventricular mechanical delay (OR, 1,037; 95% CI, 1,005-1,071; р=0,017) and longitudinal strain of interventricular septum mid segment (OR, 0,726; 95% CI, 0,540-0,977; р=0,035) had an independent relationship with SR. According to the ROC analysis, the sensitivity and specificity of model in SR prediction were 77,3% and 91,3% (AUC=0,862; p<0,001).Conclusion. SR is associated with both LBBB mechanical patterns assessed by STE and TDI. LBBB defined by ECG did not have significant association with SR to CRT.
Greater response to cardiac resynchronization therapy in patients with true complete left bundle branch block: a PREDICT substudy
