Objective To explore the clinical value of different patterns of complete left bundle branch block (CLBBB) evaluated by two-dimensional speckle tracing echocardiography (2D-STE) in predicting acute response of chronic congestive heart failure (CHF) patients with cardiac resynchronization therapy (CRT).
Methods A total of 36 patients with CHF and CLBBB by CRT were selected and conducted with echocardiography examination in the ON and OFF states of CRT, and the increase of left ventricular ejection fraction (LVEF) ≥ 5% at ON state of CRT was defined as responsive, while the increase of LVEF < 5% was defined as unresponsive. According to the longitudinal time-strain curve types of left ventricular posterior interventricular septum, CLBBB was divided into type Ⅰ, type Ⅱ and type Ⅲ. Patients with type Ⅰ and type Ⅱ were set as study group 1, patients with type Ⅲ were set as study group 2, and the conventional ultrasound parameters, systolic function parameters and systolic asynchrony parameters were detected at the OFF state of CRT.
Results Among the 36 patients, there were 29 cases (80.56%) with response and 7 cases (19.44%) without response; there were 20 patients with type Ⅰ CLBBB, 4 patients with type Ⅱ, and 12 patients with type Ⅲ. There were 22 patients with effective response to acute response of CRT in the study group 1, and the effective rate of response was 91.67% (22/24); in the study group 2, 7 patients had effective response to acute response of CRT, and the effective rate of response was 58.3% (7/12); the effective rate of response to acute response of CRT in the study group 1 was significantly higher than that in the study group 2 (P < 0.05). There were no significant differences in left ventricular diameter, left ventricular systolic function, left ventricular diastolic function and ventricular asynchrony parameters between the two groups (P>0.05). The overall longitudinal peak strain of the interventricular septum and the overall longitudinal peak strain of the lateral wall in the study group 1 were significantly lower than those in the study group 2 (P < 0.05). The standard deviation of the peak time of left ventricular strain at 18 segments in the study group 1 was significantly greater than that in the study group 2 (P < 0.05).
Conclusion There are differences in response efficiency of acute response among different types of CLBBB; the response efficiency of acute response in type Ⅰ and Ⅱ CLBBB is better than that of type Ⅲ CLBBB; the function of interventricular septum and left ventricular sidewall in type Ⅰ and Ⅱ CLBBB is better than that of type Ⅲ CLBBB; the left ventricular systolic asynchrony of type Ⅰ and Ⅱ CLBBB is more significant than that of type Ⅲ CLBBB.
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