Drug-eluting stents versus bare metal stents for angina or acute coronary syndromes

Coronary artery disease generally results from the build-up of fatty material and other substances on the internal surface of the blood vessels which supply the heart, gradually reducing its supply of oxygen. There may or may not be associated pain (angina). The disease may cause sudden death and limit normal daily activity. One strategy used to control symptoms or restore blood supply is Percutaneous Transluminal Coronary Angioplasty (PTCA) in which a small elongated balloon is inflated at the site of the plaque, compacting the deposited material against the vessel wall. This review explores the effects of one category of interventional device used with PTCA: coronary artery stents. These are expandable devices resembling a tubular wire mesh used to 'scaffold' vessels open during PTCA procedures to relieve coronary obstructions in patients. The success rates associated with these devices are high, complication rates low and most patients experience improvement in symptoms. Nonetheless, rates of restenosis (re-narrowing of the treated vessel) which may require a repeat intervention, are a significant limitation of the use of stents. An adaption of stent technology involves stents which release (elute) drugs over time in order to reduce restenosis; however these stents are expensive in comparison to their bare metal equivalent. Our review includes results from 47 studies (including more than 14,500 patients) and contains data up to five years following treatment. No statistically significant differences in death, myocardial infarction or vessel blockage were reported between drug-eluting stents (DES) and bare metal stents (BMS). Use of DES did result in decrease in the number of times patients had to be re-treated due to blockage of the blood vessel and/or stent. Thus, DES are effective in reducing rates of restenosis but are not superior to standard BMS in terms of decreasing death, myocardial infarction or thrombosis. The increased cost of DES and lack of evidence of their cost-effectiveness means that various health funding agencies are either limiting their use or attempting to regulate use in relation to their price.