A registry -which includes every patient in Sweden having
percutaneous coronary intervention (PCI) for the treatment of acute and stable
coronary artery disease- has found that PCI implantations using a new
generation of drug-eluting stents is associated with lower rates of relapse
(restenosis), stent thrombosis and subsequent mortality than older generation
drug-eluting stents and bare-metal stents.(1)
The findings, from the Swedish Coronary Angiography and
Angioplasty Registry (SCAAR), reported in the European Heart Journal, represent
the outcome of treatment in a large “real-world population”, and were
derived from an analysis of 94,384 consecutive stent implantations performed in
Sweden between November 2006 and October 2010.
An earlier study from the SCAAR registry, evaluating stent
implantations between 2003 and 2004, had dramatically shown that those treated
with drug-eluting stents (DES) had a higher rate of later mortality than those
receiving bare-metal stents (BMS).(2) The results caused uproar, and prompted
an immediate decline in the use of DES and an urgent review of their safety.
However, follow-up of the same patient cohort two years later (with data
extended to 2006) found no increased risk of death between the two groups.(3)
The difference in outcome was largely explained by improvements in cardiology
practice (including the application of dual antiplatelet therapy after PCI) and
the introduction of improved devices.
Conclusions in this latest report, from what is the world’s
largest PCI registry with the longest follow-up of data, now confirm that
mortality rates associated with both the new and old generations of DES were
significantly lower than found with BMS. The risk of death was 28% lower with
the old generation DES and 45% lower with the new generation; moreover, the new
generation DES were associated with a 23% lower mortality rate at two years
than the old generation DES.
The authors note that this is the first time any mortality
reduction has been shown between DES and BMS, either in randomised trials or in
reports from the SCAAR registry itself.
The study also found that the new generation of DES was
associated with a 38% lower risk of restenosis and a 43% lower risk of stent
thrombosis within two years of implantation than BMS. Late stent thrombosis has
been a recurring safety concern with the original DES; the authors suggest that
the new generation DES, with “thin, more biocompatible polymers” and
greater flexibility, may have contributed to lowering this thrombotic risk.
Speaking on behalf of the SCAAR investigators, cardiologist
Dr Stefan James from Uppsala University Hospital
in Sweden
described the latest findings as “intriguing” – not just because of
the lower rates of restenosis with the latest generation of DES, which were expected,
but also of stent thrombosis and mortality. “The low rates of restenosis
and stent thrombosis correspond with the results of several recent randomised
trials,” said Dr James, “and this may well translate into mortality
reduction in a sufficiently large study population.”
However, he warned that all observational data should be
interpreted with caution. “Despite the use of appropriate statistical
methods,” he said, “there may be residual confounding because of differences
in concealed baseline variables.” Nevertheless, this SCAAR analysis
included only patients who where treated after 2006, to ensure that both the
older and newer generation DES were used. “Since 2006 no major changes in
recommendations for antithrombotic strategies or duration of dual antiplatelet
therapy have occurred in Sweden,”
said Dr James, “so it seems likely that our more favourable outcomes are
true findings.”
The investigators say their results now add further weight
to the strong recommendation for the use of DES as a default strategy in
patients expected to tolerate extended dual antiplatelet therapy, in the
treatment of coronary artery disease. “But our results also reinforce the
need for randomised trials to evaluate the optimal strategy and duration of
antithrombotic therapy following PCI in various indications,” said Dr
James.
References
1. Sarno G, Lagerqvist B, Frober O, et al. Lower risk of stent thrombosis and
restenosis with unrestricted use of ‘new-generation drug-eluting stents: a
report from the nationwide Swedish Coronary Angiography and Angioplasty
Registry (SCAAR). Eur Heart J 2012; doi:10.1093/eurheartj/ehr479
2. Lagerqvist B, James SK, Stenestrand U, et al. Long-term outcomes with
drug-eluting stents versus bare-metal stents in Sweden. N Engl J Med 2007; 356:
1009-1019.
3. James SK, Stenestrand U, Lindback J, et al. Long-term safety and efficacy of
drug-eluting versus bare-metal stents in Sweden. N Engl J Med 2009; 360:
1933-1945.
* Drug-eluting stents are metallic mesh tubes which keep
open narrowed coronary arteries while slowly releasing a medication to prevent
the build-up of scar tissue inside the stent.
About the European Society of Cardiology
The European Society of Cardiology (ESC) represents more than 71,200 cardiology
professionals across Europe and the Mediterranean.
Its mission is to reduce the burden of cardiovascular disease in Europe.
Posted by Sean Fenske, Editor-in-Chief, MDT