Balancing the risks of restenosis and stent thrombosis in bare-metal versus drug-eluting stents: results of a decision analytic model.

OBJECTIVES We sought to define what incremental risk of very late stent thrombosis (VLST) in drug-eluting stents (DES) would outweigh the restenosis benefit. BACKGROUND Although there are robust data on the restenosis benefit of DES versus bare-metal stents (BMS), the incremental risk of stent thrombosis, a rare but serious complication of percutaneous coronary intervention (PCI), is not known with certainty. METHODS We developed a decision analytic Markov model comparing DES versus BMS strategies for a contemporary PCI population. Procedure-related morbidity and mortality data from published reports were used to derive the model probabilities. Over a range of incremental risk and duration of risk of VLST, we identified the net benefit of DES versus BMS in terms of quality-adjusted life expectancy (QALE). RESULTS Under an assumption of equal stent thrombosis rates beyond 1 year, the DES strategy was superior to BMS in terms of QALE (16.262 vs. 16.248 quality-adjusted life years [QALYs], difference = 0.014). Under the alternative assumption of an incremental risk difference of 0.13%/year, the net benefit was substantially reduced (difference = 0.001 QALYs). The threshold excess risk of very late DES thrombosis compared with BMS, above which BMS would be the preferred strategy, was 0.14%/year (over 4 years of follow-up). This threshold increased as the population risk of restenosis increased and decreased as the vulnerable time window lengthened. CONCLUSIONS A small absolute increase in DES thrombosis compared with BMS after 1 year (>0.14%/year) would result in BMS being the preferred strategy for the overall PCI population. Larger clinical trials with longer follow-up are needed to estimate the risk of late stent thrombosis with greater certainty for existing and new DES.