What are the diagnostic criteria for dilated cardiomyopathy?

The diagnostic criteria for dilated cardiomyopathy primarily involve evaluating the structure and function of the heart using imaging studies, particularly echocardiography. Dilated cardiomyopathy is characterized by the dilation of the heart chambers (mostly the left ventricle) and a significant reduction in the heart's ejection fraction, typically below 40%. An ejection fraction below this threshold indicates that the heart is not pumping efficiently, which is a hallmark of this condition.

Ventricular dilation is another key feature of dilated cardiomyopathy. In an echocardiogram, findings would demonstrate enlarged ventricles, reflecting the impaired contractility of the heart muscle. Therefore, the combination of ventricular dilation and reduced ejection fraction is critical for diagnosing this condition.

Other options do not fulfill the necessary criteria. A normal ejection fraction alongside ventricular dilation would not be indicative of dilated cardiomyopathy. The presence of hypertension alone does not confirm the diagnosis, as hypertension can lead to various forms of cardiomyopathy and heart disease but is not exclusive to dilated cardiomyopathy. Lastly, a cardiac stress test is not typically used as a diagnostic tool for this condition; rather, it assesses myocardial ischemia or functional capacity but does not directly measure the structural