A 69-year-old man comes to the office with a 4-week history of fatigue. He feels "drained" by the end of the day. He has no chest pain, shortness of breath, or body aches but does have decreased exercise tolerance. He reports good appetite and no recent weight changes. His medications include amlodipine for hypertension and rosuvastatin for hyperlipidemia. His temperature is 36.8 C (98.3 F) and blood pressure is 144/90 mm Hg. Body mass index is 22 kg/m².
Initial laboratory studies show hemoglobin of 14.2 g/dL, serum potassium of 4.6 mEq/L, and serum creatinine of 0.8 mg/dL. Fasting glucose level is 98 mg/dL. Electrocardiogram is shown here.
Which of the following is the best next step in management of this patient?

Question

Quizplus · Accepted Answer

This patient's presentation is consistent with atrial fibrillation (AF). Electrocardiogram shows an irregularly irregular rhythm with varying R-R intervals and no clearly discernible P waves. Patients may be asymptomatic but typically present with chest pain, dyspnea, palpitations, weakness, decreased exercise tolerance, dizziness, or presyncope. Electrocardiogram AF is the most common supraventricular arrhythmia and can occur due to a variety of cardiac and/or systemic disorders. Patients with hyperthyroidism have an increased risk of developing AF, and the risk is also increased in those with subclinical hyperthyroidism (low serum thyroid-stimulating hormone [TSH] and normal serum T4 concentration in clinically euthyroid patients). As a result, all patients with new-onset AF should have serum TSH levels obtained as part of initial evaluation for early diagnosis and appropriate management of hyperthyroidism. disorders (Choice A) Ankle brachial index measurement is used to detect peripheral arterial disease in patients with intermittent claudication. (Choice B) Patients using statin drugs (eg, rosuvastatin) can develop statin-induced myopathy with myalgia, muscle weakness, and/or elevation of serum creatine kinase levels. This patient has no such signs/symptoms. (Choice D) Treadmill exercise stress test may be used for diagnosis in patients with an intermediate probability of coronary artery disease. Atrial fibrillation is usually not associated with stable coronary heart disease and is also a relative contraindication to exercise treadmill testing. (Choice E) Urine albumin excretion is increased in patients with glomerular diseases (eg, focal or diffuse glomerulonephritis, nephrotic syndrome) and in systemic illnesses such as diabetes mellitus. The presence of albuminuria (micro or macro) has been found to be associated with a higher AF risk; however, routine measurement of urine albumin levels is not recommended. Educational objective: Patients with clinical or subclinical hyperthyroidism have a higher risk of developing atrial fibrillation (AF). Serum thyroid-stimulating hormone levels should be measured during the initial evaluation of all patients with new-onset AF. __________ References: Subclinical hyperthyroidism as a risk factor for atrial fibrillation. (http://www.ncbi.nlm.nih.gov/pubmed/11685172) Subclinical hyperthyroidism and the risk of coronary heart disease and mortality. (http://www.ncbi.nlm.nih.gov/pubmed/22529182)

A 69-Year-Old Man Comes to the Office with a 4-Week