Short left main coronary artery causing dynamic left ventricular outflow tract obstruction and new onset left bundle branch block

Introduction: Left bundle branch block can be seen in conditions like aortic stenosis, extensive coronary artery disease, primary disease of the cardiac electrical conduction system, dilated cardiomyopathy, Lyme disease; it is also associated with short left main coronary artery and dynamic left ventricular outflow tract obstruction. While the former is caused by the shearing force on septal branches of the left anterior descending artery, the latter is related to either Venturi effect in hypertrophic cardiomyopathy or effect of systolic anterior motion caused by abnormal geometric relationship of papillary muscle and the mitral apparatus.