Western Denmark Heart Registry: Rate of Stent Thrombosis With Drug-Eluting vs Bare-Metal Stents

Luis Gruberg, MD, FACC


April 26, 2007

This large, real-world experience suggests that a follow-up period of 12 months after drug-eluting stent implantation may be too brief to draw exact conclusions on the safety of these devices.

Recent reports have suggested that the risk for late-stent thrombosis is higher with drug-eluting stents (DES) than bare-metal stents (BMS). Given the lack of a consistent definition of stent thrombosis used in different trial and registry studies, new and uniform definitions were recently made by the Academic Research Consortium (ARC),[1] which defined stent thrombosis as either definite, probable, or possible ( Table 1 ).

The Western Denmark Heart Registry covers approximately 3.0 million inhabitants with 3 high-volume interventional centers for the whole region. This Registry collects detailed patient and procedural data on all coronary interventions, including bypass surgery, performed between January 2002 and June 2005. All patients were treated with dual antiplatelet therapy for 12 months and were followed out to 15 months.

The registry was designed to evaluate the risk for stent thrombosis, myocardial infarction (MI), and death following DES or BMS implantation.

Stent thrombosis was defined according to ARC criteria (defined above). MI and death were ascertained from national databases. All endpoints were adjudicated by a specialist committee.

A total of 8847 patients were treated with BMS, and 3548 patients were treated with a DES. Baseline clinical and lesion characteristics are shown in Table 2 .

The combined endpoint of definite, probable, or possible stent thrombosis was seen in 2.15% of patients treated with BMS and in 1.8% of those treated with DES (P = .57). Analysis of patients who had a definite stent thrombosis showed similar rates in both groups (Figure 1). However, when only the last 12-15 months were analyzed (after completion of dual antiplatelet therapy), the rates of definite stent thrombosis were significantly higher in patients treated with DES (Figure 1).

Western Denmark Registry: definite stent thrombosis -- overall rate and rate after 12-15 months.

The rate of target lesion revascularization was significantly higher in the BMS group, but there was no difference in the overall rates of mortality and MI between the 2 groups (Figure 2). However, when the analysis was done after 12 months, there was a significant increase in the rate of MI in patients treated with DES, with an adjusted relative risk of 4.0 (95% confidence interval [CI] 2.06-7.79; P < .0001).

Western Denmark Registry: overall rates of target lesion revascularization, mortality, and myocardial infarction.

  1. In 12,395 patients treated with recommended dual antiplatelet therapy for 12 months following DES or BMS placement, there was no difference in the rates of stent thrombosis, MI, or mortality.

  2. Use of DES was associated with a 43% relative reduction in target lesion revascularization.

  3. Between 12 and 15 months after the index percutaneous coronary intervention, there was a small but significant excess of definite stent thrombosis and MI in the DES group. The minor risk for very late stent thrombosis and MI does not outweigh the benefit of DES at 15 months follow-up, however.

The present registry of a large, "real-world experience" suggests that a follow-up period of 12 months after DES implantation may be too brief to draw exact conclusions on the safety of these devices. These results demonstrate that the important observation period associated with DES comes after the completion of dual antiplatelet therapy.

I believe that these types of registries provide us with a more accurate picture of what happens to real patients under real circumstances outside the sterile world of clinical trials. The limitations are clear and were well addressed by the study authors.

We look forward to the 2-year follow-up data to be presented at the upcoming Transcatheter Cardiovascular Therapeutics (TCT) symposia.


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