What Are the Strategies for Secondary Stroke Prevention after Transient Ischemic Attack?

The Hospitalist. 2015 December;2015(12):

December 1, 2015 | The Hospitalist

Lily Zeng, MD ; Vanderbilt University Medical Center In Nashville ; Tenn. ; And Vanja Douglas, MD

Risk factors should also be targeted in every case. Hypertension should be treated with a goal of lower than 140/90 mm Hg (or 130/80 mm Hg in diabetics and those with renal disease). Studies have shown that patients who are discharged with a blood pressure lower than 140/90 mm Hg are more likely to maintain this blood pressure at one-year follow-up.¹⁶ The choice of medication is less well studied, but drugs that act on the renin-angiotensin-aldosterone system and thiazides are generally preferred.¹⁵ Treatment with a statin is recommended after cerebrovascular ischemic events, with a goal LDL under 100. This reduces risk of secondary stroke by about 20%.¹⁷

(click for larger image)Table 3. Risk reduction goals and benefits

The goal of admitting high-risk patients is to expedite workup and initiate therapy. Two studies have shown that immediate initiation of preventative treatment significantly reduces the risk of stroke by as much as 80%.

At discharge, it is also important to counsel patients on their role in preventing strokes. As with many diseases, making lifestyle changes is key to stroke prevention. Encourage smoking cessation and an increase in physical activity, and discourage heavy alcohol use. The association between smoking and the risk for first stroke is well established. Moderate to high-intensity exercise can reduce secondary stroke risk by as much as 50%¹⁸ (see Table 3). While light alcohol consumption can be protective against strokes, heavy use is strongly discouraged. Emerging data suggest obstructive sleep apnea (OSA) may be another modifiable risk factor for stroke and TIA, so screening for potential OSA and referral may be needed.¹⁵

Back to the Case

When Mr. G arrived at the ED, his symptoms had resolved. Based on the history of expressive aphasia and right-sided weakness, he most likely had a TIA in the left MCA territory. Hemorrhage was ruled out with a non-contrast head CT. His pacemaker precluded obtaining an MRI. CTA revealed diffuse atherosclerotic disease without evidence of carotid stenosis. His ABCD2 score was six given his age, blood pressure, weakness, and symptom duration, and he was admitted for an expedited workup. His sodium and glucose were within normal limits. His hemoglobin A1c was 6.5%, his LDL was 120, and his international normalized ratio (INR) was therapeutic at 2.1. His TIA may have been due to AF, despite a therapeutic INR, because warfarin does not fully eliminate the stroke risk. It might also have been caused by intracranial atherosclerosis.

Two days later, the patient was discharged on atorvastatin at 80 mg, and his lisinopril was increased for blood pressure control. For his age group, A1c of 6.5% was acceptable, and he was not initiated on glycemic control.

Bottom Line

TIAs are diagnosed based on patient history. Urgent initiation of secondary prevention is important to reduce the short-term risk of stroke and should be implemented by the time of discharge from the hospital.

Dr. Zeng is a hospitalist in the department of internal medicine at Vanderbilt University Medical Center in Nashville, and Dr. Douglas is associate professor in the department of neurology at the University of California at San Francisco.

Key Points

TIAs usually last less than one hour but are considered warning signs for strokes; secondary prevention is key.
Advances in neuroimaging are beginning to blur the classic definition of TIAs; diffusion-weighted imaging is able to detect acute infarcts in patients who present with symptoms matching the classic definition of TIAs.
ABCD2 score works as a triage tool: A score of three or higher warrants a hospital admission. Incorporating imaging data increases the discriminatory power of stroke prediction.
Antiplatelet therapy should be initiated immediately. Blood pressure should be lower than 140/90 mm Hg at the time of discharge in a non-diabetic. Statins can be initiated in the hospital with an LDL goal of 100. Empiric atorvastatin 80 mg is an alternative approach. Diabetes control is less stringent per American Diabetes Association guidelines.
Encourage smoking cessation, exercise, and avoidance of heavy alcohol use. Consider referral for sleep study to evaluate for undiagnosed obstructive sleep apnea.