Ischemic Stroke: Secondary Prevention

One day while in Hypertension clinic, I met a patient who was referred from stroke clinic. They had multiple risk factors for a recurrence, including hypertension, dyslipidemia and a significant smoking history. Unfortunately, they had not been treated adequately for these risk factors in the past. Upon reviewing their medications, I noted they were on Aspirin alone for their secondary prevention. This interaction prompted me to review the different options for secondary prevention in stroke.

According to the Thrombosis Canada 2020 guidelines on secondary stroke prevention, in response to ischemic stroke or TIA, there are 10 major factors to consider:

1. Lifestyle Risk Factor Modification – Key behavioural changes to prevent risk of recurrent stroke include eating a balanced diet (fruits, vegetables, fibre, plant-based protein; avoiding saturated fat and cholesterol), limiting sodium intake (<2g daily), increasing exercise (at least 150 minutes per week), weight management (BMI 18.5 – 25) and limiting alcohol consumption (10 drinks per week).
2. Smoking Cessation – There is no clear evidence for the optimal time for nicotine replacement therapy initiation post-stroke. Assess patients’ readiness to change and suggest nicotine replacement when amenable, as it is generally safer than continued smoking. Additionally, prescription of nicotine replacement therapy, varenicline or bupropion may increase patients success in quitting.
3. Blood Pressure Management – Measure BP at each encounter, as hypertension is the most important modifiable risk factor for stroke. <140/90 is the target for all patients after stroke or TIA. <130/80 is the target for patients with diabetes after a stroke. In patients with lacunar stroke, aim for systolic <130.
4. Antithrombotic Therapy – All patients should have antiplatelet therapy in the form of ASA 81mg daily, ASA 25mg and dipyridamole 200mg daily, or clopidogrel 75mg daily, unless there is a contraindication to anticoagulation. Combination therapy, ASA 81mg and clopidogrel 75mg is acceptable for 1 month after stroke or TIA, but should not be continued longer, as it carries an increased risk of hemorrhagic complications. *All stroke patients should be evaluated for atrial fibrillation, which would be an absolute indication for anticoagulation.
5. Lipid Management – Statins are indicated to target LDL <2.0mmol/L or >50% reduction in LDL from baseline; target LDL <1.8mmol/L or >50% reduction in LDL in patients with acute coronary syndrome and coronary disease. If patients do not tolerate statins, or do not meet target, ezetimibe can be considered. Bile acid sequestrants and PCSK9 inhibitors can be considered in addition to statins +/- ezetimibe.
6. Diabetes Management – HbA1c should be targeted to <=7.0%. Refer to Diabetes Canada Guidelines for choice of anti-hyperglycemic agents to achieve target.
7. Sleep Apnea – Obstructive Sleep Apnea (OSA) should be screened for (STOP-BANG questionnaire) and treated, given it is a risk factor for stroke.
8. Management of Carotid Stenosis – Ipsilateral, symptomatic 50-99% internal carotid artery stenosis as measured on CT angiogram in patients with TIA or non-disabling stroke should be referred to neurosurgery/vascular surgery for evaluation. Carotid endarterectomy, if eligible, should occur within 14 days of the onset of symptoms. If stenosis is <50%, surgical management is not indicated.
9. Anticoagulation for Atrial Fibrillation – Investigations for atrial fibrillation should be completed in all patients with stroke (48-hour Holter monitor, loop recorder) and should include prolonged cardiac monitoring in patients >=55 years old.
10. Management of Patent Foramen Ovale (PFO) – Closure of PFO and antiplatelet therapy is recommended for patients 18-60 years old following an ischemic stroke or TIA linked to their PFO.

In the specific case of an ischemic lacunar stroke, given the presence of cerebral small vessel disease, recommendations are similar, yet continue to be evolving. Hypertension should be managed, but a clear target BP has not been defined. A combination of aspirin and clopidogrel is associated with increased hemorrhagic risk in these patients without corresponding advantages. Statins are effective in treating hyperlipidemia in these patients. Finally, anticoagulant and carotid surgery are not recommended ubiquitously.

This patient was referred to our clinic for hypertension management, so we mainly focused on recommendation 3 by starting a new anti-hypertensive. We were also able to encourage lifestyle modifications in recommendation 1 and validate their decision to quit smoking in recommendation 2.

When providing adequate secondary prevention after a stroke, it is important to take a holistic approach to management. 

-EB-

References:

Thrombosis Canada. Stroke: Secondary Prevention. 2020. Accessible at https://thrombosiscanada.ca/wp-content/uploads/2020/02/Stroke-Secondary-Prevention_26Feb2020.pdf 

Valenti R, Pantoni L. Secondary Prevention After Ischemic Lacunar Stroke. InIschemic Stroke Therapeutics 2016 (pp. 137-146). Springer, Cham.