What is the treatment for high-grade stenosis in the right posterior cerebral artery (PCA)?

Treatment of High-Grade Stenosis in Right Posterior Cerebral Artery

For high-grade stenosis (50-99%) in the right posterior cerebral artery, aggressive medical therapy is the definitive treatment, with aspirin 325 mg daily as the cornerstone antiplatelet agent, combined with high-dose statin therapy, blood pressure control to <140 mmHg systolic, and intensive risk factor modification. 1

Antiplatelet Therapy

Aspirin 325 mg daily is specifically recommended over oral anticoagulation for moderate to high-grade intracranial atherosclerotic stenosis (50-99%). 1 This recommendation comes from the 2023 World Stroke Organization guidelines, which represent the most current evidence-based approach.

• Anticoagulation is NOT recommended unless there is another indication such as atrial fibrillation. 1
• The evidence does not support dual antiplatelet therapy (DAPT) over single antiplatelet therapy (SAPT) for established intracranial stenosis. 1 While the SAMMPRIS trial showed DAPT was better than stenting, it did not prove DAPT superior to SAPT for chronic management. 1
• Alternative single antiplatelet agents include clopidogrel 75 mg daily or aspirin-dipyridamole 25/200 mg daily if aspirin is not tolerated. 1

Blood Pressure Management

Target systolic blood pressure <140 mmHg is specifically recommended for patients with moderate to high-grade intracranial atherosclerotic stenosis. 1 This is more stringent than general stroke prevention targets and reflects the high-risk nature of intracranial disease.

Lipid Management

High-dose statin therapy is mandatory, with a target LDL cholesterol of 1.8 mmol/L (70 mg/dL). 1 This aggressive lipid-lowering approach is essential for stabilizing atherosclerotic plaque and preventing progression.

Lifestyle Modifications

At least moderate physical activity is specifically recommended for patients with intracranial atherosclerotic stenosis. 1 Additional lifestyle interventions should include:

• Smoking cessation 1
• Mediterranean-style diet 2
• Diabetes control if applicable 1
• Weight management 2

Endovascular Intervention: NOT Recommended

Angioplasty and stenting is NOT recommended for moderate to high-grade intracranial atherosclerotic stenosis (50-99%). 1 This is a critical point that distinguishes intracranial from extracranial carotid disease management.

• The SAMMPRIS trial definitively showed that aggressive medical therapy is superior to stenting for intracranial stenosis. 1
• Perioperative complication rates with intracranial stenting are substantial, with stroke or death rates of 9.5% in meta-analyses. 1
• While individual case reports describe successful PCA stenting 3, 4, 5, these represent anecdotal evidence that cannot override guideline-level recommendations against routine intervention.

Imaging Surveillance

Serial non-invasive imaging with MRA or CTA is recommended to monitor disease progression and detect new lesions in the posterior circulation. 6 MRA or CTA is specifically preferred over ultrasound for evaluating posterior circulation vessels. 1, 6

Common Pitfalls to Avoid

• Do not confuse this with cardioembolic stroke mechanisms that might warrant anticoagulation. 6 PCA stenosis is an atherosclerotic process requiring antiplatelet therapy.
• Do not pursue endovascular intervention based on stenosis severity alone, as medical therapy has proven superior outcomes. 1
• Do not use inadequate aspirin dosing. The specific recommendation for intracranial stenosis is 325 mg daily, not the lower 81 mg dose used for general stroke prevention. 1

Prognosis Context

Patients with symptomatic PCA stenosis face a stroke rate of approximately 6.0 per 100 patient-years of follow-up, which is lower than basilar (15.0) or vertebral artery stenosis (13.7) but still represents significant risk. 7 This underscores the importance of aggressive medical management.