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ePaper - CCN Ausgabe - Number 1/2012

Ausgabe 1 - Number 1 · 2012 BIK INFORMATION www.ccn-info.comwww.ccn-info.comwww.ccn-info.com CCNCCNCCNCCNCCNCCNCCNCCNCCNCCNCCNCCN Current Evaluation of the Scientific Data for Drug-eluting Stents (DES) and Drug-eluting Balloons (DEB) Prof. Dr. med. Sigmund Silber Cardiology Practice and Hospital, Munich, Germany Email: sigmund@silber.com Background: Percutaneous coronary intervention (PCI) is an established component in the treatment of coronary artery disease. Presently, in more than 95% of coronary interventions worldwide coronary stents are implanted. It should be stressed that stent implantation represents a decision effecting the rest of a patient´s life. The explantation or „recall“ (such as can apply to pacemaker / defibrillator units or heart valves) of a stent later deemed defect or even dangerous is not possible. For this reason the product selection, particularly of drug-eluting stents (DES), should be carefully considered on the basis of scientific data. In recent years, an alternative to stent implantation is becoming increasingly established: drug-eluting balloon catheters (DEB) in many cases circumvent a stent and thus the implantation of „unnecessary metal in the coronary arteries.“ Due to the rapid development in the field of DES and DEB, the objective of this paper is to survey the current CE-certified and commercially available products in Germany, including updates on the newest scientific findings regarding their evaluation level. Methods: The highest scientific relevance is awarded to a prospective, randomized, controlled trial with a primary clinical endpoint. Often, however, surrogate parameters are used as the primary endpoint for „logistical reasons.“ The sample size required to achieve solid validity for rando- mized trials is determined by a „power calculation“ based on the expected outcome (superiority or non-inferiority) with respect to the „power“ anticipated by the investigator and the assumed failure rate during follow-up. This „power“ usually applies only to the primary endpoint and not to the secondary endpoints or subgroup analysis. In contrast to randomized trials, registries have no simultaneous (!) control group. Since unknown „interference factors“ in historic comparison collectives cannot be ruled out, a sample size calculation in a strictly scientific sense is not possible in registries. The term used in registries is thus primary test parameters instead of primary endpoints. It is often argued that ran- domized studies do not reflect reality due to their patient selection - as opposed to registry trials. But this no longer holds true for the recently more frequent „all-comers“ randomized trials. Also, „true reality“ is not shown in registry studies simply because of the selection of study centers. Based on these considerations the evaluation levels for randomized trials and registries, a simplified scheme of the „evidence-based medicine scores“1 , were chosen as listed in Table 1. Indications for DES: Due to the excellent data regarding several DES, implantation of DES is now the preferred strategy in the ESC PCI Guidelines with a class IA recommendation level („DES with proven efficacy should be considered by default in nearly all clinical conditions and lesion subsets“).2 The previously common restriction to specific vessel diameters or lesion lengths is no longer appropriate. Based on current scientific data Table 2 lists the selection available depending on the evaluation level. The question regarding the point at which a stent modification can be deemed „minor“ or „major“ remains.3 Accordingly, there are no randomzied trials regarding Resolute Integrity modifications or Xience Prime. The everolimus-eluting, PLLA- based, bioresorbable „Absorb scaffold“ though CE-certified is not yet widely available.4 Relative contraindications regarding a DES implantation: DES require a strict and - to prevent stent thrombosis - an „extended“ dual platelet aggregation inhibition (DAPT), i.e. the combination of ASA with a P2Y12 receptor antagonist (clopidogrel or prasugrel or ticagrelor). The optimal duration for a DAPT after implantation of a DES is still uncertain, but (in patients with stable CAD) it should last at least 6 months.19 Table 3 lists the clinical situations in which according to the ESC Definition of the Evaluation Level Evaluation Level Randomized, controlled trial •with primary clinical endpoint •which was also achieved •published or accepted for publication in a „peer-reviewed journal“ •if so far only presented at a large convention or submitted for publication, the evaluation level is indicated in parentheses. This also applies to publications in supplements. +++ or (+++) Randomized, controlled trial •with primary angiographic endpoint •which was also achieved •published or accepted for publication in a „peer-reviewed journal“ •if so far only presented at a large convention or submitted for publication, the evaluation level is indicated in parentheses. This also applies to publications in supplements. ++ or (++) Registry Trial •published or accepted for publication in a „peer-reviewed journal“ •if so far only presented at a large convention or submitted for publication, the evaluation level is indicated in parentheses. This also applies to publications in supplements. + or (+) Table 1: Definition of the evaluation levels of clinical trials depending on their significance as a simplified scheme of the „evidence-based medicine score.“1 46

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