We report the case of a 66-year-old African American female with a history of breast cancer previously treated with anthracycline based chemotherapy presenting with significant mitral regurgitation. She initially had preserved left ventricular systolic function with normal cardiac chamber dimensions, however, she developed progressive left ventricular chamber dilation and mild reduction in systolic function, which prompted surgical correction of her mitral regurgitation. After surgical mitral valve repair, she developed overt left ventricular failure with severe systolic dysfunction; however, she responded well to subsequent medical therapy.