Final answer:
The most common regurgitation found in patients with dilated cardiomyopathy is mitral regurgitation, where the mitral valve does not close properly allowing blood to flow back into the atrium when the ventricle contracts.
Step-by-step explanation:
The most common regurgitation found in patients with dilated cardiomyopathy is mitral regurgitation. Mitral regurgitation occurs when the mitral valve, located between the left atrium and left ventricle, does not close properly, allowing blood to flow back into the atrium when the ventricle contracts. This can lead to symptoms such as shortness of breath, fatigue, and fluid retention.