This syndrome, which can be reverted, is also one of the causes of preventable stroke, at least in the context of carotid endarterectomy. At present, there is little information on the incidence of this condition in the context of carotid stenting, which is the purpose of this study, in addition to providing tips to prevent it.

A systematic search resulted in 33 studies with a total 8731 carotid stenting procedures reporting 4.6% hyperperfusion risk (3.1 to 6.8%). Nearly half of hyperperfusion patients later had a stroke (47%), and more than half of strokes resulted fatal or disabling (54%).

Symptoms did not appear immediately after procedure, but at average 12 hours after procedure (8 to 36 hour range). This is clearly different form embolic stroke, also diagnosed in the same cath lab.

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Impaired cerebrovascular reserve was associated to higher risk of post stenting hyperperfusion syndrome (RR 5.18; CI 95% 1.0 to 26.8; p=0.049).

If the procedure takes place in the context of a symptomatic patient, the risk of periprocedural stroke is a lot higher ─this we have known for some time now. What we did not know is that evolution with hyperperfusion syndrome involves significantly lower risk of stroke compared to acute patients (RR 0.20; IC 95% 0.07 to 0.59; p=0.001).

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Patients with bilateral carotid stenosis or very critical lesions should be watched closely in the first hours after procedure, and their blood pressure needs to be monitored obsessively.

Conclusion

Cerebral hyperperfusion syndrome is relatively frequent and serious in patients undergoing carotid stenting, and it appears in the first hours after procedure, never immediately. We should encourage further research to find out how to treat this phenomenon, and also how to control blood pressure and measure cerebral blood flow.

Original title: Cerebral Hyperperfusion Syndrome After Carotid Artery Stenting: A Systematic Review and Meta-analysis.

Reference: Anne E. Huibers et al. Eur J Vasc Endovasc Surg (2018). Article in press.

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