This case study describes an unusual cause of acute heart failure that resolved with early beta-blockade therapy. A 52-year-old woman who had acute heart failure with severe left ventricular systolic dysfunction and left bundle branch block was admitted to a university medical center. Contrast-enhanced magnetic resonance images of the heart did not show any evidence of myocardial infarction or myocarditis. Rate-related left bundle branch block and subsequent left ventricular dyssynchrony resulted in acute systolic dysfunction that resolved with beta-blockade therapy that allowed heart rate control and narrowing of the QRS complex. Of note, the use of inotropic agents would have dramatically worsened the cardiac condition.