Late thrombosis of paclitaxel-eluting stents: long-term incidence, clinical consequences, and risk factors in a cohort of 604 patients

Abstract

Background: Late thrombosis is the major safety concern of drug-eluting stents, but its incidence in common clinical practice remains controversial to date, especially beyond the first year after stent implantation. We sought to investigate the incidence, clinical consequences, and risk factors of late thrombosis after drug-eluting stent implantation.

Methods: Consecutive patients (N = 604) who received > or = 1 paclitaxel-eluting stent(s) (PES) between June 2003 and February 2005 at our institution were enrolled. Clinical characteristics and major outcomes were reviewed to detect cases and predictors of late and very late definite PES thrombosis (LDT) of PES, as currently defined by the Academic Research Council.

Results: During long-term follow-up (median 34.3 months, IQR 8.6), 17 cases of LDT were noted (cumulative incidence 2.8%, 95% CI 1.7%-4.5%). Most of LDT were very late thromboses (14 cases, 82%). Late and very late definite PES thrombosis appeared at a steady rate (incidence density 1.1% patient-years). Late and very late definite PES thrombosis was related to a high risk of all-cause death (HR 3.2, 95% CI 1.3-7.9) and cardiac death (HR 6.0, 95% CI 2.3-15.6). Withdrawal of antiplatelet therapy, left ventricular ejection fraction, and average stent diameter per patient were independent predictors of LDT in multivariate analysis.

Conclusions: Late and very late definite PES thrombosis may be more frequent in a real setting than anticipated by initial experimental and observational studies but is keeping with more recent scientific evidence. It seems to occur at a constant rate during long-term follow-up and is associated with a high risk of overall and cardiac death.