A 56-year-old man comes to the emergency department an hour after sudden onset of left hemiparesis that resolved completely in 30 minutes. The patient has not seen a physician for many years and takes no medications. Two years ago, he was told that his blood pressure was elevated during a visit to the dentist. The patient has a 30-pack-year smoking history and drinks 1 or 2 cans of beer daily. He has a sedentary lifestyle and a diet consisting mostly of fast food. The patient's father had a stroke at age 60. Blood pressure is 170/95 mm Hg and pulse is 94/min. BMI is 34 kg/m2. Physical examination is normal. ECG shows sinus rhythm with no acute ischemic abnormalities, and noncontrast CT scan of the head reveals no hemorrhage. Serum LDL is 165 mg/dL and hemoglobin A1c is 7.5%. Which of the following is the greatest risk factor associated with this patient's neurological condition?
Modifiable risk factors for TIA & ischemic stroke | |
Risk factor | Estimated attributable risk |
Hypertension | 4× |
Smoking | 2.5× |
Diabetes mellitus | 2× |
Hypercholesterolemia | ≤2× |
Alcohol intake | Variable/inconsistent effect |
Sedentary lifestyle, obesity | Small effect |
TIA = transient ischemic attack. | |
This patient's acute hemiparesis suggests transient ischemic attack (TIA), a self-limited episode of neurologic impairment due to CNS ischemia without infarction. Both TIA and acute ischemic stroke most commonly are caused by atherosclerotic cerebrovascular disease. As with atherosclerotic disease elsewhere (eg, coronary artery disease), cerebrovascular disease is a multifactorial disorder and patients commonly have multiple risk factors; however, the single greatest attributable risk factor in most patients is hypertension.
Hypertension causes elevated shearing forces on the intracerebral vascular endothelium, which accelerates the atherosclerotic process and promotes thrombi formation. Patients with hypertension have up to a 4-fold increase in risk of stroke compared to normotensive individuals.
Ideal risk factor management requires addressing all modifiable risk factors concurrently, but patients who have numerous risk factors (such as this patient) may be reluctant to initiate so many interventions at once. In such cases, lowering blood pressure (eg, DASH diet, antihypertensive medications) usually should be prioritized because even mild reductions of blood pressure can diminish stroke risk (up to 40% with a reduction of 10 mm Hg in systolic blood pressure and 5 mm Hg in diastolic blood pressure).
(Choice A) Heavy alcohol intake is associated with increased risk for TIA and stroke. Evidence regarding mild or moderate consumption (eg, 1 or 2 drinks daily) is mixed, and any effect is likely small.
(Choice B) After hypertension, smoking is one of the most important risk factors for TIA and stroke, with a relative risk of approximately 2.5. The risk normalizes within approximately 4-5 years of cessation.
(Choice C) Diabetes mellitus is associated with an approximately 2-fold increase in stroke risk. Strict glycemic control does not provide a significant reduction in risk.
(Choice D) Hypercholesterolemia is an important risk factor for TIA and ischemic stroke, and statins (eg, atorvastatin) are effective in preventing recurrent events. However, the attributable risk is less than that of hypertension.
(Choices E and G) Family history and sedentary lifestyle are associated with increased risk of stroke, but the effect is largely related to other risk factors (eg, hypertension). The direct attributable risk is small.
Educational objective:
Transient ischemic attack and acute ischemic stroke are most commonly due to atherosclerotic cerebrovascular disease. Patients usually have multiple risk factors, but hypertension typically is the most important. Risk factor management should prioritize lowering blood pressure because even mild reductions can diminish stroke risk.