Outcome in patients previously on antithrombotic therapy in the SAMMPRIS trial: subgroup analysis

Abstract

Background and purpose: Stenting has been used as a rescue therapy in patients with intracranial arterial stenosis and a transient ischemic attack or stroke when on antithrombotic therapy (AT). We determined whether the stenting versus aggressive medical therapy for intracranial arterial stenosis (SAMMPRIS) trial supported this approach by comparing the treatments within subgroups of patients whose qualifying event (QE) occurred on versus off of AT.

Methods: The primary outcome, 30-day stroke and death and later strokes in the territory of the qualifying artery, was compared between (1) percutaneous transluminal angioplasty and stenting plus aggressive medical therapy (PTAS) versus aggressive medical management therapy alone (AMM) for patients whose QE occurred on versus off AT and between (2) patients whose QE occurred on versus off AT separately for the treatment groups.

Results: Among the 284/451 (63%) patients who had their QE on AT, the 2-year primary end point rates were 15.6% for those randomized to AMM (n=140) and 21.6% for PTAS (n=144; P=0.043, log-rank test). In the 167 patients not on AT, the 2-year primary end point rates were 11.6% for AMM (n=87) and 18.8% for PTAS (n=80; P=0.31, log-rank test). Within both treatment groups, there was no difference in the time to the primary end point between patients who were on or off AT (AMM, P=0.96; PTAS, P=0.52; log-rank test).

Conclusions: SAMMPRIS results indicate that the benefit of AMM over PTAS is similar in patients on versus off AT at the QE and that failure of AT is not a predictor of increased risk of a primary end point.

Clinical trial registration url: http://www.clinicaltrials.gov. Unique identifier: NCT00576693.

Keywords: antiplatelet agents; intracranial arteriosclerosis; stroke.

© 2015 American Heart Association, Inc.

Figures

Figure 1

Kaplan-Meier curves for the primary endpoint in the two treatment groups for patients taking an antithrombotic at the time of the qualifying event.

Figure 2

Kaplan-Meier curves for the primary endpoint in the two treatment groups for patients taking aspirin and clopidogrel at the time of the qualifying event.

Figure 3

Kaplan-Meier curves for the primary endpoint in the two treatment groups for patients not taking an antithrombotic at the time of the qualifying event.