Which finding on a chest X-ray would indicate dilated cardiomyopathy?

The presence of cardiomegaly on a chest X-ray is a significant finding that suggests dilated cardiomyopathy. In this condition, the heart chambers, especially the left ventricle, become enlarged and weakened, which results in an increase in overall heart size as seen on imaging. Dilated cardiomyopathy is characterized by the dilation of the heart muscle, leading to impaired systolic function. This enlargement is often one of the earliest indicators noted on a chest X-ray, providing a visual confirmation of the changes occurring in the heart structure due to the disease.

While pleural effusion can occur in various cardiac conditions, including heart failure resulting from dilated cardiomyopathy, it is nonspecific and does not directly indicate the presence of the condition itself. Aortic enlargement is more characteristic of conditions related to aortic pathology, such as hypertension or aortic regurgitation, rather than dilated cardiomyopathy. A normal heart size would be inconsistent with a diagnosis of dilated cardiomyopathy, as the condition inherently leads to an increase in heart size due to the dilation of the myocardial chambers.