A 45-year-old woman comes to the clinic complaining of shortness of breath and palpitation on exertion for 3 years. Physical examination reveals that cardiac dullness border enlarges laterally and inferiorly, and cardiac dullness border is boot-shaped. The cause for her symptoms is most likely to be A: aortic regurgitation B: cor pulmonale C: dilated cardiomyopathy D: isolated mitral stenosis E: hypertensive heart disease