TUM – Technical University of Munich Menu
Ein Stent.
Mit solchen Stents werden Blutgefäße erweitert. (Bild: marvinh/©iStockphoto.com)
  • Research news

After bypass surgery: Drug-eluting stents not superior to bare-metal stents in the long-run

Advantage of coating lost after first year

In bypass surgery, alternative routes are built around blocked heart vessels. Yet new occlusions can occur in bypasses. To re-open them, doctors use stents, sometimes coated with drugs to prevent constriction. Researchers from the German Heart Centre Munich at the Technical University of Munich (TUM) and the German Centre for Cardiovascular Research (DZHK) have investigated the long-term effect of different stent types in bypasses. They found surprising differences to native blood vessels. 

“The study results really surprised us”, says Dr. Robert Byrne, Deputy Director of the Department of Cardiovascular Diseases at the German Heart Centre Munich, a hospital of the Technical University of Munich (TUM). This is because in the first year after reopening, drug-eluting stents (DES) are clearly superior to bare-metal stents (BMS): Substantially fewer re-occlusions occur in bypasses created from patients' veins. Yet this advantage is lost in the subsequent years.

If a bypass occludes, the bypass would usually not be replaced again due to the risk associated with the surgery; instead, the occluded vessel is reopened with a catheter and a stent is inserted. The stent stabilises the vessel and is supposed to prevent its reocclusion. The significance of previous studies on what type of stent works better in vein bypasses long-term is limited, since they only investigated relatively small patient groups and the duration of the studies was too short. “Yet we must know how patients are doing in the years following the bypass’s reopening”, clarifies DZHK scientist Byrne. “After all, they will usually live for several years after treatment.” In the study, 610 patients were therefore observed over five years. 307 had a bypass with a bare-metal stent and 303 had a vein bypass with a drug-eluting stent.

Differences to native vessels

The study results distinctly differ from data from long-term observations of stents in native coronary vessels. In these cases, there are also fewer occlusions with drug-eluting stents in the five years after reopening. A reason for the divergent results in bypasses and native vessels could be the different wall structure in veins and arteries. A section of the leg vein is usually used for bypasses.

However, the coronary vessels are arteries and the two types of vessels may react differently to stenting. The diameter of arteries is also usually smaller than that of a vein bypass and drug-eluting stents demonstrated clear advantages particularly in vessels with a smaller diameter. “We therefore might not have seen any advantage of drug-eluting stents in vein bypasses at all”, says Byrne.

Recommendation remains the same

Regarding patient safety – measured by the death or myocardial infarction rate –, the scientists could not observe any differences between the two types of stents. “We still recommend a DES for patients with an occluded vein bypass, since the advantage in the first year is clear and outweighs the comparatively minor disadvantages in the subsequent years”, says Byrne. “But I think it’s important that our patients are informed about the long-term results.”

Now there is a new generation of drug-eluting stents. Based on the experience with prior models, the drug dose of these new stents is adjusted. Moreover, their struts are thinner so that there are fewer vessel lesions and their polymer coatings are better tolerated. Byrne and his colleagues are therefore planning a new study in which the long-term effect of these new DES is compared to that of bare-metal stents in vein bypasses.


Colleran, R., Kufner, S., Mehilli, J., Rosenbeiger, C., Schupke, S., Hoppmann, P., Joner, M., Mankerious, N., Fusaro, M., Cassese, S., Abdel-Wahab, M., Neumann, F. J., Richardt, G., Ibrahim, T., Schunkert, H., Laugwitz, K. L., Kastrati, A., Byrne, R. A. & ISAR-CABG Investigators . “Efficacy over Time with Drug-Eluting Stents in Saphenous Vein Graft Lesions”. Journal of the American College of Cardiology 71, 1973-1982, (2018). DOI:10.1016/j.jacc.2018.03.456


Dr. Robert A. Byrne
Department of Cardiovascular Diseases
German Heart Centre Munich
Technical University of Munich


Corporate Communications Center

Technical University of Munich

Article at tum.de

Ein Elektroauto auf dem Rollenprüfstand der Technischen Universität München.

Pacemakers on a roller test bench

Pacemakers and defibrillators are often implanted in patients with heart failure or cardiac arrhythmias to regulate heart function. These devices are susceptible to electromagnetic interference, which  can potentially occur...

Prof. Stefan Engelhardt (r.) mit Petros Avramopoulos.

Suppression of miR-29 protects against cardiac fibrosis

Cardiac fibrosis involves an increase of connective tissue in the cardiac muscle, causing a loss of function. A team of researchers at the Technical University of Munich (TUM) has now discovered that microRNA 29 (miR-29)...

Eine schematische Zeichnung eines Herzmuskels.

An atlas of the heart

A healthy heart beats about two billion times during a lifetime – thanks to the interplay of more than 10,000 proteins. Researchers from the Max Planck Institute of Biochemistry (MPIB) and the German Heart Centre at the...

Computergrafik eines Herzmuskels.

Heart attacks: The dangerous first year

Heart attacks pose a greater threat to women than to men. A team at the Technical University of Munich (TUM) has determined that in the first year after a heart attack women are subject to a significantly higher mortality...

Dr. Markus Krane operiert am Deutschen Herzzentrum München mit der Ozaki-Methode. (Bild: A. Heddergott / TUM)

A template for a new heart valve

A new method allows surgeons to reconstruct entire heart valves from the patient’s own tissue. This surgical procedure is currently only used at a handful of centres in the world. Recently, PD Dr. Markus Krane, Deputy...

Aufnahme der Blutgefäße auf einem Herzmuskel.

Vanishing capillaries

Diabetics have a significantly higher risk of suffering a heart attack. A research team at the Technical University of Munich (TUM) has now identified one of the causes: Diabetes is associated with the loss of small blood...