According to study investigators, four analyses of three-year follow-up data for the landmark Arterial Revascularization Therapy Study I and II (ARTS I and II) studies, showed that drug-eluting stents (Cypher - Cordis) may be considered an appropriate alternative to coronary artery bypass surgery (CABG) in patients with multi-vessel disease. One of the analyses was presented by Principal Investigator, Professor Patrick W Serruys, Thoraxcenter, Erasmus Medical Center, The Netherlands, at the European Society of Cardiology Congress, in Vienna, Austria.
Three of these analyses sought to assess the long-term impact of the Cypher stent when the patient with multi-vessel disease was also diabetic, the length of the blockage was more than 100mm or a bifurcation blockage. A fourth analysis reported the overall incidence of stent thrombosis in the data set using the Academic Research Consortium (ARC) definitions.
The ARTS I Study was conducted in 1997 and compared the results of a bare metal stent (BMS) to those obtained with bypass surgery. The ARTS II Study included 607 patients from 45 European centres treated with the Cypher stent. Investigators compared the findings for these patients to those from the ARTS I Study, which included 605 patients treated with bypass surgery and 600 treated with a BMS.
Diabetic patients
In the subgroup analysis of diabetic patients (367 patients or 20% of the total ARTS I and II patient populations), clinical investigators found similar rates of freedom from major adverse cardiac and cerebrovascular events (MACCE) for the Cypher stent and CABG out to three years of follow-up. This finding is significant as MACCE (comprised of death, stroke, myocardial infarction) and the need for revascularisation at one-year follow-up was the primary endpoint of the ARTS II study. Specifically, 72.1% of the diabetic patients who received the Cypher stent remained free of MACCE three years after the procedure, compared to 82.2% of the patients in the bypass surgery arm (p=0.09). Additionally, the Cypher stent performed significantly better than the BMS arm during the same endpoint, as 52.7% of the patients who received a BMS did not experience a MACCE event after three years. The difference between the Cypher stent arm and the BMS arm reached statistical significance (p=0.0003).
Blockages >100mm
Clinical investigators also reported no significant impact on MACCE when Cypher stents were implanted in patients with blockages that measured more than 100mm in length (20% of the ARTS II patient population). According to this subgroup analysis, 75.8% of these patients remained free of MACCE out to three years of follow-up, compared to 82.5% of the patients who received Cypher stents measuring 100mm or less in length (p=0.15).
Bifurcations
A third analysis showed that implantation of the Cypher stent in bifurcations did not affect clinical outcomes. The rate of freedom from MACCE for patients who received a Cypher stent to treat a bifurcation (53.4% of the overall patient population) was 79.8%, compared to 81.5% when the implantation did not take place in a bifurcation (p=0.61). The clinical investigators also found that neither the type of bifurcation (true/substantial or partial) nor the stent implantation strategy (one- or two-stent implantation) significantly influenced MACCE outcomes. The freedom-from-MACCE rate for true bifurcations was 81.9%, compared to 78.1% for partial bifurcations (p=0.58). The one-stent implantation strategy produced a freedom from MACCE rate of 82.0%, compared to 79.3% for the two-stent strategy (p=0.60). Bifurcations are associated with increased case complexity.
ARC definitions
In addition, the ARTS II Study investigators reported stent thrombosis rates for the Cypher stent using the ARC definitions. The definite, definite/probable and definite/probable/possible stent thrombosis rates for the Cypher stent at three years were 3.3%, 5.3% and 6.4%, respectively. Stent thrombosis comparisons between the Cypher stent and the BMS were not possible as ARC stent thrombosis rates for the ARTS I Study were not available and the ARTS I Study did not track stent thrombosis rates beyond 30 days. The protocol stent thrombosis rate for the BMS arm was 2.8% at 30 days of follow-up, while the ARC definite definite/probable and definite/probable/possible stent thrombosis rates for the Cypher stent at 30 days were 1.0%, 1.5% and 1.5%, respectively.
In lieu of ARC stent thrombosis rates for the BMS, the clinical investigators pointed out that the rate of myocardial infarction for the Cypher stent was significantly lower than that of the BMS (3.6% for the Cypher stent vs. 6.8% for the BMS, p=0.014). In addition, the mortality rate for the Cypher stent was numerically lower than that of the BMS, although this difference did not reach statistical significance (3.0% for the Cypher stent vs. 4.0% for the BMS, p=0.33). These rates favoured the Cypher stent in spite of the fact that the patients treated with the drug-eluting stent were significantly more complex than the patients treated with the BMS.
"These analyses contribute significantly to medical understanding of clinical outcomes for the Cypher stent in patients with multivessel disease, who remain one of the most complex patient populations with coronary artery disease to treat," said Serruys.
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