Cardiac resynchronization therapy for exercise-induced left ventricular dysfunction in the setting of left bundle branch block: A case report and review of the literature

Exercise-induced dyspnea is one of the most common symptoms that cause a patient to see a physician and a broad differential diagnosis is required. In this case report, we describe a patient with this complaint who had a left bundle branch block and preserved left ventricular function at rest. On stress echocardiography, she had significant exercise-induced left ventricular dysfunction and associated mitral regurgitation but a coronary angiogram demonstrated normal coronary arteries. Both of the echocardiographic findings, as well as her symptoms, improved with the placement of a bi-ventricular pacemaker. A brief review of the literature on cardiac resynchronization therapy for indications beyond the current guidelines is also provided.