Which of the following is a potential complication of untreated hyperthyroidism?

Untreated hyperthyroidism can lead to a variety of complications due to the excessive levels of thyroid hormones in the body, which significantly affect cardiovascular function. One major potential complication is heart failure. The increased metabolic rate and elevated heart rate associated with hyperthyroidism can cause the heart to work harder. Over time, this sustained strain can lead to conditions such as cardiomyopathy or heart failure, where the heart is unable to pump blood effectively.

In contrast, hypotension is generally associated with conditions that lower blood pressure and might not be a direct result of hyperthyroidism. Sleep apnea could be a concern in terms of overall health, but it is not a known direct complication of hyperthyroidism. Likewise, hepatitis is not associated with hyperthyroidism, as this condition specifically relates to inflammation of the liver and lacks a direct connection to thyroid hormone excess. Therefore, heart failure stands out as a significant and direct complication stemming from the effects of untreated hyperthyroidism.