What is a key mechanism by which alcohol contributes to dilated cardiomyopathy?

• A. Alcohol destroys microvilli brush border leading to nutritional deficits (thiamine)
• B. Alcohol directly causes myocardial infarction
• C. Alcohol reduces afterload and prevents dilation
• D. Both microvilli destruction causing thiamine deficiency and direct myocyte toxicity contribute to DCM

Answer: (D)

Alcoholic cardiomyopathy occurs from two main pathways working together. First, chronic alcohol use often leads to malnutrition and thiamine (vitamin B1) deficiency. Thiamine is essential for myocardial energy production; when deficient, heart muscle cells don’t generate enough ATP, which can cause a form of heart failure that progresses to a dilated, weakened ventricle. This is the beriberi component of the picture, commonly associated with high-output states that can advance to dilated cardiomyopathy.

Second, alcohol itself exerts a direct toxic effect on the heart muscle. Ethanol and its metabolites injure cardiomyocytes, promote oxidative stress, and disrupt mitochondrial function, contributing to chamber dilation and reduced systolic function.

Together, these nutritional and direct toxic effects explain how alcohol can lead to dilated cardiomyopathy, making the combined mechanism the best description. It’s not about directly causing a myocardial infarction, and alcohol doesn’t prevent dilation; the microvilli/brush-border route is more about thiamine deficiency from malnutrition rather than a direct mechanism of cardiomyopathy.