Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.

A 57-year-old man is seen for follow-up evaluation after results of a carotid ultrasound obtained to investigate a left neck bruit show a mixed density plaque at the origin of the left internal carotid artery. Stenosis is estimated to be 60% to 80%. He has had no focal neurologic symptoms or visual loss. The patient has coronary artery disease (CAD) with stable angina, hypertension, dyslipidemia, type 2 diabetes mellitus, and mild kidney failure. He has a 30-pack-year smoking history but stopped smoking 7 years ago when CAD was diagnosed. Medications are aspirin, metoprolol, lisinopril, metformin, and nitroglycerin, as needed. He was taking rosuvastatin but discontinued the medication 2 years ago after developing muscle aches.

On physical examination, blood pressure is 132/78 mm Hg, pulse rate is 78/min and regular, and respiration rate is 16/min. The left neck bruit is unchanged. Cardiopulmonary examination has normal results. All other findings from the general medical and neurologic examinations are unremarkable.

Which of the following is the most appropriate next step in management?

A. Carotid endarterectomy
B. Magnetic resonance angiography of the neck
C. Resumption of statin therapy
D. Substitution of clopidogrel for aspirin

MKSAP Answer and Critique

The correct answer is C. Resumption of statin therapy.

This patient should be restarted on statin therapy for primary prevention of stroke and myocardial infarction. The patient has type 2 diabetes mellitus and coronary artery disease, and patients with these disorders benefit from high-intensity statin therapy to reduce the risk of atherosclerotic cardiovascular disease, including myocardial infarction and stroke. High-intensity statins also are recommended for patients with stroke or transient ischemic attack of a presumed atherosclerotic subtype (although this patient is not symptomatic). With improvements in medical therapy, particularly statins, the risk of stroke has been declining in patients with asymptomatic internal carotid artery (ICA) stenosis. In a recent study, the use of a statin in patients with this diagnosis was associated with a stroke risk of less than 2% per year. Although this patient developed apparent statin myopathy from rosuvastatin, switching to another statin less associated with statin myopathy is appropriate.

Although carotid endarterectomy may benefit some patients with greater than 60% asymptomatic ICA stenosis, its effectiveness is highly dependent on the patient’s underlying risks and those associated with the procedure itself. The benefit of carotid surgery is modest in patients without symptoms, and this patient’s multiple medical comorbidities make him a relatively poor surgical candidate. Some studies have suggested that additional clinical factors increase the risk of stroke further in patients with asymptomatic carotid stenosis, including rapidly progressive or greater than 80% stenosis, asymptomatic infarcts on brain imaging, or abnormal results of transcranial Doppler ultrasonography. However, the role that these factors should play in clinical decisions about treatment of asymptomatic carotid stenosis has not been established. Carotid revascularization with either endarterectomy or stenting can be considered in patients at low risk for perioperative cardiovascular morbidity.

Magnetic resonance angiography (MRA) of the neck is inappropriate in this patient because an additional diagnostic test is unlikely to change the medical management of his condition. The accuracy of MRA without contrast is likely similar to that of carotid ultrasonography.

No clear evidence supports the superiority of clopidogrel over aspirin for the primary prevention of stroke in the setting of asymptomatic ICA stenosis.

Key Point

• Using a statin to treat patients with asymptomatic internal carotid artery stenosis is associated with a stroke risk of less than 2% per year.

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