Abstract
Noninvasive diagnosis of coronary artery disease in patients with left bundle branch block is challenging. Multislice computed tomography can be useful in this population; however, quality of images depends on the patterns of myocardial contractions. We investigated the influence of left bundle branch block on image quality of multislice computed tomography coronary angiography. Multislice computed tomography coronary angiography was performed in 30 patients with left bundle branch block and 30 patients without conduction disturbances. Image quality of each coronary segment was visually assessed and rated on a five-point scale (1=highest quality). Average image quality score in the best cardiac cycle phase did not differ significantly between groups (1.71+/-0.59 in the left bundle branch block group vs. 1.60+/-0.57 in the control group, P=0.46). In the left bundle branch block group, a significantly lower image quality score was observed in end-systolic cardiac phase (2.67+/-0.6 vs. 2.22+/-0.65 in the control group, P=0.007), whereas no difference was demonstrated in mid-diastolic phase (1.73+/-0.6 vs. 1.69+/-0.66 in the control group, P=0.81). After image assessment in multiple cardiac phases, an increase in image quality score was higher in the left bundle branch block than in the control group (0.2+/-0.17 vs. 0.11+/-0.14, P=0.003). A negative correlation was observed between image quality score and both the heart rate and heart rate variability in both groups (P<0.001). A nonsignificantly lower overall image quality of multislice computed tomography coronary angiography was demonstrated in the left bundle branch block group. In the presence of left bundle branch block, image quality in the end-systolic phase was significantly lower. Image assessment in multiple phases increased overall image quality and is therefore advisable in patients with left bundle branch block. Increased heart rate and heart rate variability worsened image quality in both groups.
Highlights
Left bundle branch block (LBBB) is an electrical conduction disturbance that can be present both in healthy patients and patients with various cardiovascular diseases [1]
In the left bundle branch block group, a significantly lower image quality score was observed in end-systolic cardiac phase (2.67±0.6 vs. 2.22±0.65 in the control group, P=0.007), whereas no difference was demonstrated in mid-diastolic phase (1.73±0.6 vs. 1.69±0.66 in the control group, P=0.81)
After image assessment in multiple cardiac phases, an increase in image quality score was higher in the left bundle branch block than in the control group (0.2±0.17 vs. 0.11±0.14, P=0.003)
Summary
Left bundle branch block (LBBB) is an electrical conduction disturbance that can be present both in healthy patients and patients with various cardiovascular diseases [1]. Data from epidemiological studies suggest that bundle branch block, especially LBBB, is an independent risk factor for cardiovascular morbidity and mortality in patients with heart diseases [2]. Detection of coronary artery disease (CAD) in this patient population in particular has obvious implications for management. Noninvasive detecting of myocardial ischemia in patients with LBBB remains challenging due to low accuracy of commonly used noninvasive diagnostic tools, such as stress electrocardiographic (ECG) study, myocardial perfusion imaging, and stress echocardiography. Exercise ECG is not reliable in this patient population due to low specificity [3]. Atypical anteroseptal wall motion challenges the interpretation of inducible wall motion abnormalities on stress echocardiography [5]
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