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ESC Congress 2003: Antibiotic drug, Sirolimus, released from a stent prevents re-narrowing of coronary arteries

September 01, 2003

IMPORTANT: This press release accompanies both a presentation and an ESC press conference given at the ESC Congress 2003. Written by the investigator himself/herself, this press release does not necessarily reflect the opinion of the European Society of Cardiology

ESC Congress 2003: Hot Line II - Acute coronary syndromes / percutaneous coronary intervention

Coronary artery disease is the cause of about half of all deaths in the general adult population. The coronary arteries are the vessels which supply the heart muscle (the myocardium) with the amount of blood it needs to maintain its function as the central "blood pump" of the human body. A variety of conditions - e.g. hypertension, an excess of blood lipids, or diabetes - may cause deposits from the blood to adhere to the artery walls, thereby narrowing the vessel lumen and impeding blood flow to the myocardium. Depending on the severity of vessel narrowing (medical term: "stenosis"), the patient may experience chest pain (angina pectoris) or, in the worst case, a heart attack (a "myocardial infarction"). Diseased coronary arteries are treated by dilating the narrowed (stenosed) segment with a small balloon which is navigated through the body into the afflicted coronary artery by way of a catheter and then inflated at high pressure. To maintain patency of the dilated coronary artery segment, a tube-like structure of metal (stainless steel) filaments called a stent is usually implanted at this site. Within weeks, a thin layer of wall tissue optimally covers the interior of the stent.

Unfortunately, as a consequence of wall injury, the "Achilles heel" of stent implantation is proliferative growth of wall tissue through the stent meshes into the vessel lumen. This may cause unwanted re-narrowing ("restenosis") of a technically successfully treated coronary artery segment and it occurs in 20-50 percent of patients within six to eight months. To possibly suppress proliferative tissue growth at the stented site, pharmacological agents have been developed which are released from the stent within weeks of stent implantation. One such agent is Sirolimus, also known as Rapamycin. Sirolimus can be immersed in a polymer coating covering the surface of a stent. The study that we performed utilised such a stent in a randomised comparison with a stent of identical architecture but without the drug-eluting coating.

Our study went by the acronym of E-SIRIUS, which stands for "European multicenter randomised, double-blind study of the SIRolImUS-coated balloon-expandable stent in the treatment of patients with de novo native coronary artery lesions". It was conducted under the supervision of the Principal Investigators Profs. Schofer (Hamburg, Germany) and Breithardt (Münster, Germany) at 35 hospitals all over Europe and enrolled a total of 352 patients, 175 of whom received the stent, whereas the remaining 177 patients were treated with the uncoated, bare-metal, (the "control") stent. The study was sponsored by Cordis Belgium.

The E-SIRIUS protocol called for all patients to undergo a repeat investigation in the catheter laboratory after 8 months to check the patency status of the treated coronary artery segment. As it turned out, 42 percent of all patients who received the uncoated stent exhibited restenosis, defined as a greater than 50 percent re-narrowing of the coronary artery lumen at the treatment site. In stark contrast, only 6 percent of patients treated with the coated stent showed restenosis. This corresponds to a striking relative reduction by 86 percent in the incidence of restenosis! Consequently, the incidence within 9 months of major adverse cardiac events ("MACE") - which comprise deaths, myocardial infarctions and repeat interventions at the original treatment site - was also significantly reduced in patients treated with the coated stent (8 percent as opposed to 23 percent in "control" patients). Thus, our study has confirmed the previously demonstrated efficacy of the Sirolimus-eluting coated stent

Our findings are all the more remarkable since the patients enrolled in E-SIRIUS represent a more "challenging" cohort than patients studied in previous clinical trials involving the coated stent. This means that factors known to carry an increased risk for restenosis were more prevalent in E-SIRIUS patients. In particular, compared with patients previously studied, our patients had longer lesions in smaller coronary arteries and they received more often multiple stents. Moreover, they were "sicker" in the sense that significantly higher percentages of patients had already experienced a myocardial infarction before enrolment and were current smokers.

In E-SIRIUS, we have also addressed, for the first time, an important procedural issue. There are two ways to implant a stent. The conventional way has been described above and consists of balloon-dilating the culprit coronary lesion first (so-called "predilatation") and then place the stent. However, the stent, which is pre-mounted on a balloon catheter, may also be implanted directly without predilatation (so-called "direct stenting"). In 26 percent of the E-SIRIUS patients, 45 of whom received the coated stent and 47 the bare-metal "control" stent, the investigators chose this latter approach. Neither for the coated stent nor for the "control" group did we find statistically significant differences in the restenosis rates and the MACE rates between the direct stenting and the predilatation approach. However, in the the coated stent subgroup of patients who underwent direct stenting we observed a tendency towards lower rates of restenosis (2.4 percent vs 7.2 percent in patients whose lesions were predilated) and MACE (4.4 percent vs 9.2 percent). We therefore conclude that direct stenting appears to be as efficacious and safe as predilatation plus stenting. In addition to the fact that direct stenting saves costs by foregoing the extra balloon catheter needed for predilatation, the direct approach may also be clinically more beneficial for patients who receive the coated stent.

Professor Joachim Schofer
Center for Cardiology and Vascular Intervention, Hamburg,
Germany

European Society of Cardiology (ESC)