Across a range of stent retriever designs and diameters there were no differences in subarachnoid hemorrhage rates.
Postthrombectomy subarachnoid hemorrhage (PTSAH) after the use of stent retrievers for middle cerebral artery (MCA) stroke is associated with more stent-retriever passes, distal device positioning, and the presence of severe iatrogenic vasospasm, a retrospective study has found.
Based on these results, “neurointerventionalists need to balance the risk of placing a stent retriever in a more distal position, doing additional passes after observation of severe vasospasm and in very tortuous anatomy versus risk/expected clinical outcome of being unable to achieve recanalization,” lead author Perry P. Ng, MD (CHPG Neurosciences and Spine, Lakewood, CO), told Neurovascular Exchange.
Ng and colleagues, whose results were published a online June 21, 2018, in the Journal of NeuroInterventional Surgery, conducted a retrospective observational study that included 85 consecutive patients. All were aged 18 or older, had thromboembolic occlusion of the MCA, at least one stent retriever pass beginning in an M2 branch, postprocedural CT or MRI scan within 24 hours, and nonenhanced CT Alberta Stroke Program Early CR Score of at least 5.
In all, eight patients had PTSAH on follow-up imaging and 77 did not. No differences in baseline characteristics were identified between the two groups.
No Differences Between Stent Designs or Diameters
The researchers identified several factors associated with increased risk for PTSAH. A greater proportion of patients with hemorrhage had two stent retriever passes (62.5% vs 18.2%; P = 0.01); the average number of passes was 3.3 for the group with hemorrhage and 1.8 for those without.
A greater proportion of patients with hemorrhage also had a stent retriever positioned 2 cm or more along an M2 branch (100% vs 30.2%; P = 0.002). In addition, more than one-third of those with hemorrhage (37.5%) had severe iatrogenic vasospasm before stent-retriever thrombectomy pass compared with only 5% of patients without hemorrhage (P = 0.02).
Procedures were performed with Solitaire (Medtronic Neurovascular; n = 36), Trevo (Stryker Neurovascular; n = 54), and MindFrame (Medtronic Neurovascular; n = 5). No difference in hemorrhage occurrence was found for different stent retriever design, diameters, or lengths, a result that Ng said was surprising.
“We expected to find some difference in the occurrence of PTSAH with stent retriever design and diameter but could not show this as our study was underpowered with only eight patients that had PSTAH,” he said.
Finally, there was no difference in good clinical outcomes based on discharge disposition or NIHSS score between the two groups. However, the researchers noted that one patient developed a sizeable left Sylvian fissure hematoma and PTSAH, and experienced neurological decline within hours after the procedure, with an increase in NIHSS score of 9 points. Over the ensuing 72 hours, the patient gradually improved to an NIHSS score of 1 with administration of cryoprecipitate and platelets and without the need for surgical evacuation of the hematoma.
Helpful, but More Research Needed
According to Ng, prevention of procedural complications is desirable for any interventional or surgical procedure.
“Although the majority of post-stent retriever SAH cases have benign outcome, it can result in clinical worsening, as demonstrated in one of our patients who had large Sylvian fissure hematoma,” Ng said.
This study has helped to identify three procedural factors associated with the occurrence of PTSAH: stent retriever placement greater than 2 cm into an M2 branch, very tortuous MCA anatomy, and severe iatrogenic vasospasm prior to subsequent thrombectomy pass, he noted.
Although these factors cannot be entirely avoided, one of the goals of the study was to try to identify intraprocedural factors that could be used to reduce the occurrence of PTSAH. However, Ng acknowledged that more research is needed to confirm these findings.
This study was limited by several factors including image quality that prohibited measurement of stent retriever position in some patients and the requirement of imaging within 24 hours of thrombectomy. “It is possible that a small PTSAH might have resolved or redistributed during this time and be missed, resulting in an underestimation of its incidence,” Ng and colleagues conclude.
Sources:
Ng PP, Larson TC, Nichols CW, et al. Intraprocedural predictors of post-stent retriever thrombectomy subarachnoid hemorrhage in middle cerebral artery stroke. J NeuroIntervent Surg. 2018;Epub ahead of print.
Disclosures:
Ng reports no relevant conflicts of interest.