The full clinical impact of calcification patterns on response to therapy and outcomes remains unclear.
Patients with acute ischemic stroke who have a predominantly medial intracranial carotid artery calcification (ICAC) pattern may be among those who benefit most from endovascular therapy, according to a post hoc analysis of MR CLEAN published online November 9, 2018, ahead of print in Stroke.
In a joint email to Neurovascular Exchange, lead author Kars C.J. Compagne, BSc, and senior author Daniel Bos, MD, PhD (both from Erasmus University Medical Center, Rotterdam, the Netherlands), explained that efforts are ongoing to determine which patient characteristics influence the outcome of endovascular therapy for acute ischemic stroke.
In this light, ICAC “has recently received much interest given its high prevalence in the middle-aged and elderly population and its role as an important risk factor for stroke,” they shared. “Moreover, recent reports showed the existence of two distinct morphological patterns of ICAC which can be visualized by CT, namely calcification of the tunica intima and calcification of tunica media.”
To determine if these calcification patterns affect the outcome of endovascular therapy, the investigators evaluated data from the MR CLEAN trial. For 344 patients in this trial, baseline noncontrast CT imaging results were available for evaluation of the volume and location pattern of ICAC.
Calcification pattern was found to have an impact on treatment effect (P for interaction = 0.04). Patients with predominantly medial calcification had better functional outcomes of endovascular therapy, as assessed via 90-day mRS, than those who did not receive endovascular therapy (adjusted OR 2.32; 95% CI 1.23-4.39).
Among patients with predominantly intimal calcifications, however, treatment with versus without endovascular therapy did not improve functional outcomes (adjusted OR 0.82; 95% CI 0.40-1.68).
There was also no association found between ICAC volume and functional outcome (adjusted OR per unit increase in volume 1.01; 95% CI 0.89-1.13), nor was there evidence for effect modification by ICAC volume (P for interaction = 0.61).
The investigators cautioned that before considering potential changes in current practice, the findings should be replicated, noting that the differences between calcification patterns “should be further investigated in terms of their pathophysiology and their exact role in stroke development and therapy after stroke.
“An important limitation of our post hoc study,” they continued, “is the limited number of patients for each group (medial, intimal, and no calcification), and therefore our results require replication in larger cohorts. Also, we were the very first to study the effect of calcification pattern on endovascular treatment, which limits our [ability] to compare our findings to other studies. Yet, we hope that our findings are hypothesis-generating and provide a basis for further studies on this topic.”
Some important unanswered questions relate to how and why certain calcification patterns develop, how a tendency to develop one pattern or another might affect stroke risk, and how development of calcification can be prevented, they noted.
Compagne KCJ, Clephas PRD, Majoie CBLM, et al. Intracranial carotid artery calcification and effect of endovascular stroke treatment: MR CLEAN subgroup analysis. Stroke. 2018;Epub ahead of print.
Compagne and Bos report no relevant conflicts of interest.