The development and refinement of coronary stenting over the last 20 years has allowed angioplasty to be performed more safely and effectively. The first stents introduced served as metal scaffolding, holding the vessel wall open. These "bare metal" stents, BMS, represented a major advance over balloon angioplasty alone by dramatically reducing, but not eliminating, the incidence of gradual vessel re-narrowing (restenosis). Restenosis is a challenging problem, with many patients ultimately requiring repeat heart catheterization, re-stenting, and in some cases, bypass surgery.

Drug eluting stents (DES) are identical in structure to bare metal stents but are coated with medications which are slowly released into the diseased artery wall, dramatically reducing the incidence of restenosis. Drug eluting stents, first released in 2003, were quickly regarded as a monumental advance in interventional cardiology. These devices have become the stent of choice in the majority of procedures in recent years, reducing repeat hospitalization, repeat heart catheterizations, and bypass surgeries.

The most important potential complication with all coronary stents is the sudden clotting of a the stented vessel (stent thrombosis), which unlike restenosis, is an acute event almost always presenting as a heart attack, and associated with high mortality. With bare metal stents, most stent thromboses will occur early after implant, typically within the the first month. It has been recognized that stent thrombosis following drug eluting stents can occur in a later time frame (up to one year or later). Although stent thrombosis is multifactorial, the combination of aspirin and Plavix has been shown to dramatically reduce the incidence of this complication. These drugs are therefore prescribed for a longer duration than with bare metal stents (usually 6-12 months).

The risk of late thrombosis with DES has been recognized since their introduction, but it was generally believed that the overall risk of thrombosis was equal when compared to BMS. Recent publications in both the scientific literature and lay press have challenged this belief and suggested that the overall risk of stent thrombosis is higher with DES. This has led to tremendous hype and understandable hysteria. This is not a resolved issue and much of the long-term data is very reassuring. The Food and Drug Administration will be holding special sessions to study this in more detail. In the meantime, it is critical for patients and cardiologists alike to keep in mind the following:

1. Stent thrombosis is a serious but fortunately rare event which occurs with both stent types—bare metal and drug-eluting. It is not definitely established that the risk of thrombosis differs between BMS and DES. The time distribution of thrombotic events, however, is different as detailed above. Patient compliance with aspirin and Plavix (or Ticlid) is critical in all cases.
2. Drug-coated stents do dramatically reduce the incidence of stent restenosis and the need for repeat procedures, including bypass surgery. Restenosis and its treatments are not benign.
3. For many patients, the risk/benefit ratio of drug-eluting stents will remain favorable and DES will remain the therapy of choice.

Medical research in the field of cardiology is fast-paced with new advances and milestones being reached frequently. We at the Cardiovascular Center of Hampton Roads will strive to provide the latest in therapeutic options while doing our best to educate our patients.

References:
www.fda.gov/cdrh/news/091406.html - FDA statement on coronary DES

www.bostonscientific.com - Manufacturer of the Taxus drug-eluting stent.

www.cordis.com - Manufacturer of the Cypher drug-eluting stent