Recurrent flash pulmonary edema due to rate-dependent left bundle branch block

Left bundle branch block (LBBB) is an electrophysiological abnormality that can have profound acute and chronic hemodynamic effects. Intermittent LBBB has been noted to occur with accelerations in heart rate, typically during exercise (known as rate-dependent LBBB). This has been associated with acute deteriorations in cardiac systolic function through the development of left ventricular (LV) dyssynchrony, and also episodic chest pain (“painful LBBB syndrome”). We present a case of an acute rate-dependent LBBB-associated cardiomyopathy with recurrent episodes of systolic heart failure and “flash” pulmonary edema that was successfully treated with cardiac resynchronization therapy (CRT).