A study recently published in The Journal of the American Medical Association (JAMA) has found that mechanical thrombectomy for posterior circulation distal, medium vessel occlusion (DMVO) is a reasonable, safe, and technically feasible therapy option.
The “Thrombectomy for Primary Distal Posterior Cerebral Artery Occlusion Stroke” (TOPMOST) study is a multicentre case-control study analysing patients treated for primary distal occlusion of the posterior cerebral artery (PCA) of the P2 or P3 segment.
A total of 23 comprehensive stroke centres across Europe, the USA, and Asia participated in this study between January 2010 and June 2020. All patients included—a total of 243—received either mechanical thrombectomy or standard medical treatment, with or without intravenous thrombolysis (IVT).
Investigators noted that they conducted their study because “clinical evidence of the potential treatment benefit of mechanical thrombectomy for posterior circulation DMVO is sparse.”
Of the 243 patients included in the study, 184 were treated with mechanical thrombectomy. Within this group the median age was 74, and 95 (51.6%) were women. A total of 149 (81%) of patients presented with posterior circulation DMVOs located in the P2 segment of the PCA, and 35 (19%) in the P3 segment of the PCA.
The researchers’ clinical endpoint was the improvement (measured as a decrease) of National Institutes of Health Stroke Scale (NIHSS) scores at discharge. Additionally, their safety endpoint was the occurrence of symptomatic intracranial haemorrhage (sICH) and haemorrhagic complications, classified based on the Second European-Australasian Acute Stroke Study (ECASSII). Furthermore, their functional outcome was evaluated with the modified Rankin Scale (mRS) score at 90-day follow-up.
At discharge, the mean NIHSS score decrease in the standard medical treatment cohort was −2.4points, and in the mechanical thrombectomy group the mean decrease was −3.9 points. The difference in the mean decrease between these groups was then −1.5 points (p=0.06).
The study authors note that “significant” treatment effects of mechanical thrombectomy were observed in the subgroup of patients whose NIHSS scores on admission were 10 points or higher (mean difference, −5.6; 95% confidence interval [CI], −10.9 to −0.2; p=0.04) and in patients not eligible for IVT (mean difference, −3.0; 95% CI, −5.0 to −0.9; p=0.005). sICH occurred in 4.3% of each treatment cohort.
The investigators concluded: “This study suggested that, although rarely performed at comprehensive stroke centres, mechanical thrombectomy for posterior circulation DMVO is a safe and technically feasible treatment option for occlusions of the P2 or P3 segment of the PCA compared with standard medical treatment with or without IVT.”
Lead author of the study Lukas Meyer, department of Diagnostic and Interventional Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, comments: “This international research collaboration represents the first international multi-centre case-control study comparing best medical treatment and mechanical thrombectomy for distal medium vessel occlusions of the posterior cerebral artery in the P2 and P3 segment. The results are promising and show that mechanical thrombectomy may be a beneficial treatment option for these distal occlusions. Furthermore, the study provides important insights of subgroups in this special patient cohort and builds a fundament for a possible near-future randomised trial in this area.”