Long term follow up of additional Swedish registry data does not indicate an increased

Four years of follow up including additional patients in the Swedish Coronary angiography and angioplasty registry (SCAAR) does no longer indicate any increased mortality in patients treated with drug eluting stents compared to patients treated with bare metal stents.

Treatment with drug eluting stents was associated with a slightly increased risk of death or myocardial infarction after the initial six months but this was compensated by a lower event rate during the initial six months. The previously reported increased risk of death associated with these stents occurred only during the initial years after their approval and release on the market. In patients who have received these stents more recently, no increased risk was observed.

Despite the fact that there is no net increase in the risk of death or myocardial infarction after 4 years there seems to be a continuous low risk of approximately 0.5 % annually of acute closure of the stents due to blood clot formation explaining the slightly higher risk of late myocardial infarction with these stents. This necessitates treatment with drugs inhibiting blood clot formation for a longer period of time. The risk of re-narrowing of the stents at the end of follow up was reduced by approximately 4% (4 cases of symptomatic renarrowing less out of 100 treated patients) compared to bare metal stents.

“This is a unique presentation of the entire experience of the long-term outcome of treatment with different types of stents in an entire country from 2003 to 2006. Despite the increased risk of acute blood clot formation in the stents which may lead to myocardial infarction there was no increase in mortality at long term follow-up.

The risk of re narrowing of the treated vessel and the need for repeated interventions was lower with the drug eluting stents but the difference was lower than previously shown in randomized comparative studies with selected patients undergoing mandated angiography control. Our opinion is therefore that drug eluting stents are not dangerous but they should be used with selection considering the individual risk of re-narrowing and the patients ability to tolerate clot inhibiting drugs for a long period of time as well as the increased cost associated with this treatment” states the investigators from Uppsala Clinical Research Centre (UCR).

The Swedish Coronary Angiography and Angioplasty Registry (SCAAR) records consecutive patients from all centres performing coronary angiography and percutaneous coronary interventions (PCI) in Sweden. Funding is obtained from the Swedish Health Authorities and the registry is completely independent of commercial funding. The technology is developed and administered by Uppsala University Clinical Research Centre (UCR). The present study included all 13786 patients in Sweden who had undergone implantation with drug eluting stent as compared to the 21480 treated with bare metal stents from January 1, 2003 until December 31, 2005 for whom at least one year of follow-up was available. Follow up was achieved by merging with other National registries. There was a range in the use of drug eluting stent from 1% to 52% between different hospitals, which was the factor with the largest influence on the selection of type of stent. During the entire study period 2957 myocardial infarctions and 1424 deaths occurred which were the outcome events used in the statistical analysis. The outcome results were adjusted for differences in background characteristics.

Today balloon dilatation with implantation of a stent is a very common and effective treatment of patients with heart attacks and angina pectoris caused by narrowing of the coronary vessels. Compared to balloon dilatation alone the use of stents has improved the safety of the procedures and reduces the need for recurrences. Over the last 4 – 5 years the stents have been covered by drugs that further reduce the reoccurrence of narrowing and the need for new procedures. Treatment with such “drug-eluting” stents has become very frequent and has been used in around 8 million patients world-wide.

Reference:
The most commonly used drug-eluting stents are based on the drugs Paclitaxel (Taxus express® and Taxus Liberté®, Boston Scientific inc.) and Sirolimus (Cypher® and Cypher Select® - Cordis, Johnson &Johnson inc.)

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