Cardiac Resynchronization Therapy Relieves Intractable Angina Due to Exercise-Induced Left Bundle Branch Block Without Left Ventricular Systolic Dysfunction: A Detailed Case Study.

Exercise-induced left bundle branch block is rare and can be demonstrated with exercise testing. When the heart rate reaches a certain threshold, the QRS widens into left bundle branch block. This paper describes a patient with exercise-induced left bundle branch block related angina and dyspnea, who responded to cardiac resynchronization therapy. We documented the potential benefits of cardiac resynchronization therapy with a left ventricular rapid pacing study prior to its implantation. Although exercise-induced left bundle branch block is not a current indication for cardiac resynchronization therapy in patients such as ours, it could be considered when conventional drug therapy fails.