Which of the following comorbidities could preclude a patient from being a candidate for heart transplant?

Active tobacco use is a significant factor that disqualifies a patient from being considered for a heart transplant. This is largely due to the increased risks associated with continued smoking, including complications that can arise during and after the transplantation process. Tobacco use can severely impair wound healing, increase the risk of infection, and adversely affect the long-term outcomes of the transplant. Transplant programs typically require patients to demonstrate a commitment to quitting smoking for a designated period prior to being placed on a transplant list.

In contrast, age over 60, while potentially considered in assessing risk, is not an absolute disqualifier. Many patients over 60 can still be viable candidates for transplantation based on their overall health and functional status. Controlled diabetes is generally not an exclusion criterion either, as managed diabetes can often have minimal impact on transplant eligibility. Similarly, low cholesterol levels are typically not a concern; in fact, having lower cholesterol could be beneficial in the context of overall cardiovascular health.