Kara Jo Swafford, MD

Compagne KCJ, Clephas PRD, Majoie CBLM, Roos YBWEM, Berkhemer OA, van Oostenbrugge RJ, et al. Intracranial Carotid Artery Calcification and Effect of Endovascular Stroke Treatment: MR CLEAN Subgroup Analysis. Stroke. 2018

Endovascular thrombectomy (EVT) is an effective treatment for patients with acute ischemic stroke caused by a large vessel occlusion. The pattern and quantity of intracranial carotid artery calcification (ICAC) may influence the effectiveness of EVT and functional outcome. There are two recognized patterns of ICAC: intimal and medial calcification patterns. Compagne et al. performed a post hoc analysis of data from MR CLEAN (Multicenter Randomized Clinical trial of Endovascular treatment of Acute ischemic stroke in the Netherlands) investigating the effect of ICAC volume and pattern on treatment success and functional outcome. Intervention and control groups were included.

There was no modification of the EVT treatment effect by ICAC volume, and no association between ICAC volume and functional outcome. There, however, was a treatment effect modification by ICAC pattern (P interaction=0.04). Patients with a medial ICAC pattern had larger infarct volumes and poorer outcomes in the control group, but tended to benefit more from EVT compared to patients with an intimal ICAC pattern. One explanation for a greater EVT treatment effect in patients with a medial calcification pattern is that this pattern can lead to arterial stiffening, causing impaired regulation of distal flow and development of microcollaterals. Another proposed explanation is that the thrombus is different in patients with intimal versus medial calcifications and EVT is not as effective in removing thrombus in those with an intimal calcification pattern.

Infarct volumes in the EVT group did not differ between the two ICAC patterns. There, however, may be a reduced benefit of EVT in reducing infarct volume in patients with intimal ICAC due to plaque disruption and microemboli formation leading to secondary injury during stent retrieval. There was no difference in adverse events or symptomatic intracerebral hemorrhage between patients in the control and EVT groups with a medial calcification pattern. For patients with an intimal calcification pattern, serious adverse events occurred more often in the EVT group, but the difference was not significant.