Reduction in mortality and target-lesion revascularisation at 2 years: A comparison between drug-eluting stents and conventional bare-metal stents in the “real world”

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Abstract

Background

Long-term safety of drug-eluting stent (DES) is still a concern. We aimed to assess the impact of DES use on all-cause mortality and target-lesion revascularisation (TLR) in routine clinical practice.

Methods

Retrospective analysis of all patients undergoing percutaneous coronary intervention with stent implantation at our institution between January 2003 and December 2004. To account for differences in patient characteristics, logistic regression was used to produce a propensity score for DES group membership. Patients receiving DES were then matched to patients receiving bare metal stents (BMS) with identical propensity scores. These two groups were then compared with respect to the incidence of TLR and all-cause mortality.

Results

During the study period 995 patients received DES. Of these, 82 patients had combined DES and BMS use and were therefore excluded; leaving 913 DES patients compared to 2105 BMS patients. Patients who received DES were more likely to be diabetic, hypertensive, had more lesions treated, restenotic lesions treated, left anterior descending and left main stem interventions, long lesions treated, small diameter lesions treated, and American Heart Association C-type lesions treated. After performing propensity-matching, to account for differences in patient characteristics, we were able to successfully match 777 DES patients to 777 BMS patients. The TLR rates at 24 months were significantly lower for DES patients (DES-4.2% vs BMS-9.2%, p < 0.001). All-cause mortality was also significantly lower for DES patients (DES-1.8% vs BMS-4.0%, p = 0.01).

Conclusions

In routine clinical practice DES implantation continued to demonstrate a significant reduction in the need for repeat intervention at 24 months. All-cause and cardiac mortality was also significantly lower for DES patients compared to BMS patients.

Introduction

The long-term clinical effectiveness of bare metal stents (BMS) has been limited by the occurrence of instent restenosis. The effect of which can mean further coronary intervention in more than 30% of several patient sub-groups, including diabetics, patients with small coronary vessels, or long lesions [1], [2], [3]. The use of drug-eluting stent (DES) technology however, with its suppression of neointimal growth, has had a dramatic impact on both the incidence of angiographic restenosis and the need for repeat revascularisation [4], [5], [6], [7], [8]. Initial case series demonstrated virtual elimination of clinically significant instent restenosis in simple lesions [9] whilst randomised control trials in more complex cases demonstrated impressive improvements in restenosis rates, with target lesion revascularisation (TLR) performed in less than 5% of DES patients [10], [11]. Major adverse cardiac events (MACE) during the first 2 years after percutaneous coronary intervention (PCI) have also been shown to be reduced significantly in patients receiving DES compared with BMS although they are driven primarily by the reductions in TLR rather than more serious irreversible events [12].

The subject populations however represented in these early clinical trials were highly selected and intentionally excluded certain complex patients. A small number of registries have reported sustained improvements in target vessel revascularisation (TVR) rates and MACE events in real world populations although subgroup differences in diabetic patients and those with long lesions or those undergoing bifurcation procedures did not achieve statistical significance [13], [14], [15].

Recent studies, including a meta-analysis of randomised trials of DES, and a large observational study (SCAAR registry), reported increased risks of death and stent thrombosis associated with DES use [16], [17], [18], [19], [20].

In clinical practice, DES are being used preferentially in complex and higher-risk cases and data in broader patient populations is important in confirming sustained benefit in the day to day practice with regards to TLR rates and to also assess the mortality rates of these patients. This latter point has become important following the recent meta-analysis by Nordmann and associates [18] which concluded that preliminary evidence suggested an increased risk of mortality in DES patients compared to BMS.

In this study we aim to investigate the impact of DES use in comparison to BMS use on TLR and all-cause mortality using a propensity matched cohort method in a large ‘real world’ PCI population at a single UK regional cardiac centre.

Section snippets

Patient population

Between 1st January 2003 and 31st December 2004, 3100 patients underwent PCI with coronary stent deployment at the Cardiothoracic Centre, Liverpool. Nine hundred and ninety-five patients had at least one DES used (with a total of 1980 DES implanted). Of these, 82 patients also received BMS devices and therefore were excluded from the study, leaving 913 patients in the DES group. The remaining 2105 patients were treated solely with BMS devices (with a total of 3738 BMS implanted). All baseline

Baseline and procedural characteristics

Baseline and procedural characteristics of the 3018 patients in the study are listed in Table 1. Patients who received DES were younger than patients in the BMS group, although this just failed to reach statistical significance. They more frequently had diabetes mellitus, and were hypertensive. Conversely, NYHA class III or IV, current smokers, acute MI and non-elective PCI was more common in the BMS group. Patients who received DES on average had a higher number of lesions treated, restenotic

Discussion

The principal findings of this study are that there was a significant reduction in mortality in patients who were treated with drug-eluting stents. In addition, there was marked reduction in the need for rates of clinically-driven target lesion revascularisation.

In the current PCI climate there is genuine concern about the long-term safety of drug-eluting stents. In a recent randomised trial meta-analysis [18], Nordman and associates reported a trend towards an increased risk of overall

Acknowledgments

We would like to acknowledge the co-operation of all Consultant Cardiologists at the Cardiothoracic Centre-Liverpool and thank all those involved in interventional cardiology data collection at the hospital.

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