SAMMPRIS trial update: only a small subset of patients may be eligible for treatment with intracranial stenting


A study published ahead-of-print in Stroke has identified risk factors for the increased risk of stroke with percutaneous transluminal angioplasty and stenting (PTAS) that was seen in the SAMMPRIS (Stenting and aggressive medical management for preventing recurrent stroke in intracranial stenosis) study. However, if all patients with these risk factors were excluded from receiving intracranial stenting, only a small subset of patients would remain.

The enrolment of the SAMMPRIS study was stopped prematurely after it emerged that PTAS (with the Gateway PTA Balloon Catheter and Wingspan Stent System, Boston Scientific/Stryker) in patients with intracranial stenosis was associated with a high risk of stroke or death within 30 days of enrolment compared with medical management. The aim of the new study by SAMMPRIS investigators David Fiorella (Department of Neurosurgery, State University of New York, Health Sciences Center, Stonybrook, USA) and others was to analyse the patient, lesion, and procedural characteristics that were associated with the periprocedural cerebral ischaemic and haemorrhagic events in patients who underwent PTAS. 

Of the 213 patients who underwent the procedure, 30 had a periprocedural stroke (11 symptomatic haemorrhages and 19 ischaemic strokes). In a multivariate analysis, higher percent stenosis, low modified Rankin score (mRS), and clopidogrel (Plavix, Sanofi-Aventis and Bristol-Myers Squibb) load associated with activated clotting time (ACT) >300 seconds were all associated with haemorrhagic strokes. Fiorella et al reported: “Of note, patients with basilar stenosis had a 20.8% rate of ischaemic events versus 6.7% for other arteries (p=0.01). Smoking status was a highly significant variable (p=0.002) with higher rates of ischaemic events among never smokers (18.1%) than former smokers and current smokers.” They explained that a possible reason for the “smokers paradox” (ie, the seemingly protective effective of smoking) may be that, in SAMMPRIS, non-smokers were more likely to be diabetic, female, and hypertensive (thus, have an increased risk of ischaemic stroke) or another reason may be that smokers might have been more responsive to clopidogrel because “smoking induces the hepatic cytochrome P450 system that is involved in the conversion of clopidogrel to its active metabolite.”

The authors added that patients with non-perforator stroke or transient ischaemic stroke at baseline had higher rates of ishaemic events than patients with perforator stroke events at baseline. They noted: “Importantly, SAMMPRIS showed no relationship between perforator stroke presentation and the risk of perforator stroke post PTAS that is, including patients with perforator stroke presentation in SAMMPRIS does not explain the high periprocedural stroke rate in the trial as has been suggested previously.”

According to Fiorella et al, there was no correlation between the time from qualifying event to PTAS and risk of periprocedural ischaemic or haemorrhagic events. They wrote: “As such, these data do not suggest that a two- to three-week ‘waiting period’ [as others have suggested] after the qualifying event would have benefitted those patients in the stenting arm of SAMMPRIS.”

Concluding, Fiorella et al reported that the risk factors that they identified were “highly prevalent in the SAMMPRIS population.” They added: “Therefore, excluding patients with high-risk features from undergoing PTAS to lower the risk of periprocedural stroke would limit the procedural to very small subset of patients with intracranial stenosis. Morever, given the limitations of the present analysis, particularly the small number of events, the results should be viewed with caution and not used as the basis for clinical treatment without further confirmatory studies.”