Which of the following is NOT a cause of various forms of heart failure?

High blood sugar levels are primarily related to metabolic conditions such as diabetes and do not directly cause heart failure. While diabetes can lead to cardiovascular issues over time and can contribute to the overall risk of developing heart disease, the specific mechanisms of heart failure are more closely linked to the pumping abilities of the heart and fluid management within the body.

The other options refer to physiological changes that directly impact the heart's ability to function effectively. Changes in fluid balance can lead to overload or insufficient fluid in the body, affecting heart performance. Alterations in right-sided heart pumping pressure can cause conditions like right-sided heart failure, and changes in left-sided pumping pressure are crucial since they directly impact the heart's efficiency in circulating blood to the rest of the body.

In summary, high blood sugar levels are a risk factor rather than a direct cause of heart failure, distinguishing it from the other options that involve direct mechanical and physiological changes in heart function.