Is the distal P2 segment of the posterior cerebral artery (PCA) a dangerous location for endovascular mechanical thrombectomy?

From the Guidelines

Endovascular mechanical thrombectomy on the distal P2 segment of the posterior cerebral artery (PCA) is generally considered high-risk but may be performed in select cases. The procedure carries increased risks compared to more proximal vessel segments due to the smaller caliber, tortuous anatomy, and thinner vessel walls of the distal PCA, which elevate the chances of vessel perforation, dissection, and iatrogenic injury. Technical success rates are lower and complication rates higher in these distal vessels. However, in cases of severe neurological deficits with large vessel occlusions affecting critical brain regions, the risk-benefit ratio may favor intervention despite these concerns.

Key Considerations

• The decision should be individualized based on patient factors, stroke severity, time from symptom onset, collateral circulation status, and the neurointerventionalist's experience.
• Modern devices designed for smaller vessels (such as 3mm stent retrievers) and specialized microcatheters have improved the safety profile somewhat, but the procedure remains challenging.
• A multidisciplinary approach involving stroke neurologists and neurointerventionalists is essential to determine the optimal treatment strategy for each patient with distal PCA occlusions. According to the 2018 guidelines for the early management of patients with acute ischemic stroke 1, the use of mechanical thrombectomy with stent retrievers may be reasonable for carefully selected patients with AIS in whom treatment can be initiated within 6 hours of symptom onset and who have causative occlusion of the anterior cerebral arteries, vertebral arteries, basilar artery, or posterior cerebral arteries. However, the guidelines do not specifically address the distal P2 segment of the PCA.

Additional Guidance

• The technical goal of the thrombectomy procedure should be reperfusion to a modified Thrombolysis in Cerebral Infarction (mTICI) 2b/3 angiographic result to maximize the probability of a good functional clinical outcome 1.
• Reduced time from symptom onset to reperfusion with endovascular therapies is highly associated with better clinical outcomes 1. It is essential to weigh the potential benefits and risks of the procedure and to consider the individual patient's circumstances before making a decision. The most recent and highest quality study on this topic is the 2018 guidelines for the early management of patients with acute ischemic stroke 1.

From the Research

Safety and Efficacy of Mechanical Thrombectomy in Distal P2 Segment of Posterior Cerebral Artery (PCA)

• The distal P2 segment of the posterior cerebral artery (PCA) is a location where mechanical thrombectomy can be performed with relative safety and efficacy, as suggested by several studies 2, 3, 4, 5, 6.
• A study published in JAMA Neurology found that mechanical thrombectomy for posterior circulation distal, medium vessel occlusion (DMVO) is a safe and technically feasible treatment option, with a low rate of symptomatic intracranial hemorrhage (4.3%) 2.
• Another study published in the Journal of Clinical Neuroscience reported a high rate of successful recanalization (88.6%) and a low rate of complications in patients undergoing mechanical thrombectomy for acute distal PCA occlusion 3.
• A study published in Neuroradiology found that mechanical thrombectomy in isolated large vessel posterior cerebral artery occlusions is feasible and can achieve successful reperfusion, with a low rate of symptomatic intracranial hemorrhage (6.7%) 4.
• A study published in Acta Radiologica found that mechanical thrombectomy with first-line aspiration of symptomatic P1 and P2 occlusions is a safe and effective procedure, with a high rate of successful reperfusion (95%) and a low rate of complications 5.
• A subgroup analysis from the STAR registry published in Interventional Neuroradiology found that mechanical thrombectomy in medium-vessel posterior cerebral artery occlusions (MEVOs) can achieve successful recanalization, with a rate similar to that in MCA MEVOs, although further study and possible innovation may be necessary to improve successful PCA MEVO recanalization rates 6.

Key Findings

• Mechanical thrombectomy in the distal P2 segment of the PCA can be performed with a high rate of successful recanalization and a low rate of complications.
• The procedure is safe and technically feasible, with a low rate of symptomatic intracranial hemorrhage.
• Further study and possible innovation may be necessary to improve successful PCA MEVO recanalization rates.