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Background: Left Bundle Branch Block (LBBB) is a conductive disorder of the heart, which usually indicates underlying cardiac pathology. It is seen in dilated cardiomyopathy, coronary artery disease, and other cardiac abnormalities. LBBB appearance should trigger a thorough search for underlying cardiac abnormalities. One important highly sensitive noninvasive test used for the diagnosis of coronary artery disease in such patients is dobutamine –atropine stress echocardiography (DSE) .
Methods: In 50 patients presenting with left bundle branch block in ECG, dobutamine stress echocardiography was performed; atropine was added if target heart rate was not achieved, then coronary angiography was performed. The patients were between 40-79 years of age.
Exclusion criteria: High-risk patients, those who showed definite criteria of acute coronary syndromes; ST segment depression or elevation in ECG, persistent chest pain, and/or positive cardiac biomarkers. Moreover, those patients with poor echo windows were excluded.
Results: Sensitivity and specificity of DSE for each coronary artery were calculated as: Left anterior descending artery (LAD): sensitivity 87%, specificity 79%, false positive 21%, false negative 13%. Left circumflex artery (LCX): Sensitivity: 78%, specificity 89%, false positive 15%, false negative 22%. Right coronary artery (RCA): sensitivity 68%, specificity 89%, false positive 11%, false negative 32%.
Conclusion: DSE is an important and sensitive diagnostic test in the accurate diagnosis of ischemic heart disease (IHD) in LBBB patients. False positive results are comparatively higher in LAD disease due to abnormal septal motion in such patients. Hence, other methods are preferred if LAD involvement is suspected. Finally, DSE has a crucial prognostic value in the evaluation of coronary artery disease in LBBB patients.
Keywords: left bundle branch block, dobutamine stress echocardiography, ischemic heart disease