A 65-year-old female is admitted to the intensive care unit for chest pain where she is diagnosed with a non-ST elevation myocardial infarction. She has a history of hypertension, type 2 diabetes mellitus, hyperlipidemia, and osteoporosis. Over the last two months, she has been getting occasional chest pain on exertion. She also complains of some recent fatigue and mild constipation. Cardiac catheterization is performed and shows severe triple-vessel coronary artery disease. A coronary artery bypass graft procedure (CABG) is planned. Her laboratory values include the following:
Which of the following is the most appropriate next step in the management of this patient?

Question

A 65-year-old female is admitted to the intensive care unit for chest pain where she is diagnosed with a non-ST elevation myocardial infarction.  She has a history of hypertension, type 2 diabetes mellitus, hyperlipidemia, and osteoporosis.  Over the last two months, she has been getting occasional chest pain on exertion.  She also complains of some recent fatigue and mild constipation.  Cardiac catheterization is performed and shows severe triple-vessel coronary artery disease.  A coronary artery bypass graft procedure (CABG) is planned.  Her laboratory values include the following:
 Which of the following is the most appropriate next step in the management of this patient?

Quizplus · Accepted Answer

Explanation: This patient's morning cortisol level is at the higher end of normal and her HbA1c is only slightly above goal level, neither of which present much risk for her planned CABG. Her elevated TSH and low total T4 do however confirm the presence of previously undiagnosed hypothyroidism. There is a risk that hypothyroidism may worsen perioperative outcomes, although urgent or emergent surgeries can usually be done on patients with hypothyroidism as long as there are no symptoms of myxedema coma or other findings to suggest severe hypothyroidism. Treatment with levothyroxine can increase myocardial oxygen demand resulting in myocardial infarction, angina, or cardiac dysrhythmias. Levothyroxine generally needs to be started slowly and gradually in patients with cardiac disease, which might prolong the wait for this patient's badly needed CABG. Therefore, it is probably best to do the surgery now despite her hypothyroid state, even though it might slightly increase her risk for perioperative adverse events. (Choice A) Iodine loading before surgery can be considered in patients with hyperthyroidism, not hypothyroidism. (Choice B) Giving the patient a large loading dose of levothyroxine would be dangerous since it may lead to myocardial ischemia with subsequent dysrhythmia or recurrent myocardial infarction. (Choice D) A thyroid scan is not needed to confirm a diagnosis of hypothyroidism, although it might be helpful to determine its underlying cause. It would be unnecessary to delay the patient's CABG to perform such a study. (Choice E) Given this patient's severe coronary disease she will be at risk for recurrent myocardial infarction until revascularization is performed with CABG. It is not necessary to postpone her surgery for slow initiation of levothyroxine therapy. Educational objective: Patients with coronary artery disease are at risk of myocardial ischemia when levothyroxine is first started and the medication should be started very slowly in these patients. Hypothyroidism (in the absence of myxedema coma or other severe symptoms) usually only mildly increases the perioperative risk.

A 65-Year-Old Female Is Admitted to the Intensive Care Unit