Coronary heart disease is the leading cause of death in the United States. The elderly, those older than 65 years of age, are more likely to have coronary disease and this problem will become even more pervasive as the population ages. Stenting of coronary blockages has become a conventional technique in both the emergency setting of a heart attack as well as more routine therapy to reduce chest pain. In general, there are two types of coronary stents: drug-coated (or drug-eluting stents, DES) and non-drug- coated (or bare metal stents, BMS). Placement of either type of stent requires treatment with clot- preventing medications such as aspirin and clopidogrel or prasugrel to keep them open. The latter two are newer types of medications that work in conjunction with aspirin to reduce the function of cells that help form blood clots in the body (platelets), thereby preventing clot formation on stents (stent thrombosis). Currently, the American College of Cardiology / American Heart Association recommend continuation of these medications for at least one year following DES and for at least one month following BMS placement. Initial studies comparing DES to BMS showed that by reducing scar formation around stents, DES are less likely to close up and require repeat procedures. Recruitment of elderly in these studies was limited and subjects were generally healthier when compared to the community-dwelling elderly. Despite lack of such information, the elderly routinely receive DES during cardiac procedures, requiring the obligatory one-year of anti-platelet drugs. On average, the elderly are more likely to be taking multiple medications, have a lower body weight, and have worse kidney function than the relatively healthier population in randomized trials, thereby putting them at higher risk of drug-drug interactions and unwanted bleeding. Bleeding, which was originally considered just a nuisance in the early days of stenting, has more recently been recognized to increase mortality in patients with coronary heart disease. The balance of possible increased risk of repeat procedures with the use of BMS and potentially increased risk of bleeding with long-term use of dual antiplatelet therapy needs further investigation. The Dual Antiplatelet (DAPT) Study will randomize >20,000 patients to either 12 versus 30 months of dual antiplatelet drugs. This trial is unique in that it will study all-comers, there is no upper age limit, and will collect data on bleeding, interruptions of medications, and adverse cardiac events. We intend to study the DAPT Study elderly subset and compare differences in effectiveness and risk of dual antiplatelet therapy and stent types. Data on the rate of heart attacks, stroke, repeat procedures, and bleeding from a state-mandated registry which collects information on all stenting procedures in Massachusetts will also be analyzed for 3 and 4 year follow-up. Information obtained from this project will provide guidance to physicians caring for elderly patients toward stenting and medical treatment of coronary heart disease, particularly in regards to type and duration of antiplatelet drugs.
An important aspect of the management of coronary heart disease entails placement of drug coated and uncoated stents in the heart arteries to open up blockages. Medications required to prevent the stents from clotting can also increase the risk of bleeding and safety of these stents and medication in the elderly is not entirely clear based on current available data. The goal of our project is to study the safety and efficacy of these medications and stents in the elderly as part of a 20,000 patient randomized trial of these clot prevention medications and a statewide registry that manages information on all coronary stenting procedures done in Massachusetts.
|Yeh, Robert W; Vasaiwala, Samip; Forman, Daniel E et al. (2014) Instrumental variable analysis to compare effectiveness of stents in the extremely elderly. Circ Cardiovasc Qual Outcomes 7:118-24|