Effect of Left Bundle-branch Block on Systolic and Diastolic Left Ventricular Functions With and Without Heart Failure

We designed this study to examine the effect of left bundle-branch block (LBBB) on systolic and diastolic functions of the left ventricle (LV) in patients with heart failure and in subjects with isolated LBBB.
METHODS
A comparison between 36 patients with heart failure and LBBB (group I), 36 patients with heart failure without LBBB (group II) and 41 subjects with isolated LBBB (group III) was made. Coronary angiography was performed in all patients with group I and group II, and in 20 patients of group III. LV end-diastolic pressure was calculated. Echocardiography was performed in all patients. LV ejection fraction and mean rate of circumferential shortening were calculated. The following Doppler parameters were also evaluated: peak rapid filling velocity (E wave), peak atrial filling velocity (A wave), E and A wave integrals, E wave acceleration time, deceleration time (EDT) and rates (EAR and EDR), the E/A ratio and its integral, and diastolic flow time (DT). The ejection time (ET), isovolumetric relaxation time (IRT) and preejection period were measured using the aortic and mitral flow velocities.
RESULTS
LV end-diastolic pressure was calculated as 28±4 mmHg in group I, 22±5 mmHg in group II, and: 15±3 mmHg in group III. Although the systolic function parameters in group-III patients were different, the diastolic function parameters were found to be quite similar in both patients with group II and III. Comparison with group I and group II patients showed that there was a similarity between LV systolic function parameters while the diastolic function parameters were statistically different (E/A, p=0.004; EAR, p<0.001; EDR, p<0.001; EDT, p<0.001; IRT, p=0.024; DT, p=0.03).
CONCLUSION
We confirmed that LBBB causes diastolic function impairment in subjects with isolated LBBB similar to those of patients with heart failure, and it also augments the impairment of diastolic function in patients with heart failure.