The rate of definite/probable stent thrombosis (again, by ARC definition) at 2 years in the COMPARE trial was 0.9% in the Xience V group and 3.9% in the Taxus group – higher rates than found in SPIRIT IV. Most notable, however, was a 77% reduction in very late definite/probable stent thrombosis in the Xience V arm. The rate of this outcome was 0.3% in the Xience V group and 1.5% in the Taxus Libert? group, reported Dr. Peter Smits of Maasstad Ziekenhuis.
This difference is especially notable because the vast majority of patients were no longer taking dual antiplatelet therapy at 2 years, said Dr. Smits, principal investigator of COMPARE. In contrast, more than 70% of patients in each arm of the SPIRIT IV trial remained on dual antiplatelet therapy at 2 years.
Unlike the SPIRIT design, the COMPARE trial was designed to be an “all-comer, real-world study” without exclusions for complex patients. At 2 years, the superiority of the Xience V stent for the primary end point – a composite of all mortality, nonfatal MI, and target vessel revascularization (MACE) – was maintained, with larger absolute differences between the stents than at 12 months.
At 1 year, this primary end point had occurred in 6.2% and 9.1% in the Xience V and Taxus groups, respectively, for an absolute difference of 2.9%. At 2 years, these rates rose to 9.0% and 13.7%, for an absolute difference of 4.7%. There were similar reductions in secondary end points. As in SPIRIT IV, there were no benefits of the Xience V stent for diabetic patients.
Both studies are still ongoing and will conclude with 5-year analyses.
The SPIRIT IV trial is sponsored by Abbott Vascular, and the COMPARE trial is funded by Abbott Vascular and Boston Scientific. Dr. Stone disclosed that he sits on the advisory boards for, and receives honoraria from, Abbott Vascular and Boston Scientific. Dr. Smits disclosed that he received a speaking fee from Abbott Vascular and that his cardiology department has received unrestricted research grants from Abbott Vascular and Boston Scientific. Dr. Kereiakes disclosed that he has received honoraria and grant support from both Abbott Vascular and Boston Scientific.