Response to Letters Regarding Article, “Prasugrel Plus Aspirin Beyond 12 Months Is Associated With Improved Outcomes After TAXUS Liberté Paclitaxel-Eluting Coronary Stent Placement”

Abstract

Drs Jeger and Pfisterer have asked 2 important questions: Does the increase in ischemic events we reported after cessation of dualantiplatelet therapy (DAPT) in the TAXUS Libertē Post-Approval Study (TL-PAS) patients 1 reflect a rebound risk specific to the TAXUS Liberté paclitaxel-eluting stent that may not apply to other drug-eluting stents, and did use of the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Arteries (GUSTO) bleeding definitions underestimate important bleeding in patients treated with prasugrel? Drs Shah and Buch shared their concern about bleeding, and also wondered whether the use of intravascular ultrasound (IVUS) to perfect stent placement might have diminished the need for prolonged DAPT.Comparative studies have reported higher rates of stent thrombosis with the TAXUS Liberté paclitaxel-eluting stent relative to other drug-eluting stents, 2,3 but not consistently. 4 About one-quarter of the patients in the DAPT Study 5 received TAXUS Liberté stents, nearly all of whom are represented in the TL-PAS cohort analysis. An interaction analysis within the DAPT Study found that prolonged DAPT produced consistent stent thrombosis reductions regardless of stent type (interaction P=0.76). Increased ischemic events following thienopyridine withdrawal were observed in the overall DAPT Study, not just in the TL-PAS cohort. Importantly, the majority of these adverse events were myocardial infarctions not related to the index stents, suggesting that prolonged DAPT provides secondary atherothrombotic event protection independent of stents or stent type.Combined GUSTO moderate and severe bleeding was the powered primary safety end point in the DAPT Study. The TL-PAS cohort represented the majority of patients treated with prasugrel in the DAPT Study. Rates of GUSTO moderate and severe bleeding in this cohort (2.4% with 30 months, 1.7% with 12 months DAPT) were close to rates observed in the overall DAPT Study population (2.53% with 30 months, 1.57% with 12 months DAPT). However, observations for the TL-PAS cohort were not powered; we restricted discussion of the TL-PAS cohort to GUSTO bleeding rates to be concordant with the DAPT Study, and because further descriptions using other definitions would not have greater observational power. Exploration of events using Bleeding Academic Research Consortium definitions within the DAPT Study did not alter the primary safety conclusions, and neither the DAPT Study nor TL-PAS observed increased rates of lethal or intracranial bleeding with 30 months therapy.With regard to intravascular imaging, we would note that IVUS use in TL-PAS was similar to that reported by most US hospitals 6 and that TL-PAS is, as intended, likely reflective of contemporary IVUS use. We also note that consistent benefit from routine IVUS during drug-eluting stent placement remains unproven, and it is unknown whether the routine use of IVUS would have led to different results. However, because most of the benefit of DAPT beyond 12 months appears related to th...