DRUG-ELUTING STENT SOLUTIONS: The Massachusetts Stent Study

What was the motivation behind the Massachusetts Stent study? What were your goals in conducting this analysis?
We had seen reports from observational studies in Europe, showing higher rates of adverse events associated with drug-eluting stents (DES) than with bare-metal stents (BMS) that were different from the results from randomized trials. Of course, the randomized trials showed lower restenosis rates with DES, but the size of these trials was not large enough to know for sure whether there was an increase in the rates of either myocardial infarction (MI) or death. We thought it was important to find out whether the same problems reported in some European studies were seen elsewhere. In Massachusetts, the Department of Public Health requires mandatory reporting of all percutaneous coronary intervention (PCI) procedures to monitor the quality of healthcare. By looking at these data, we had the opportunity to answer some important questions for interventional cardiologists.

How does your analysis fit into context of other “real-world” data that have been recently published (Swedish Coronary Angiography and Angioplasty Registry [SCAAR], Western Denmark Heart Registry, Strategic Transcatheter Evaluation of New Therapies [STENT] Registry, etc.)?
The Massachusetts Stent database is unique for several reasons. In the United States, there is a high rate of PCI, and there has been a very rapid adoption of DES. We found that at the beginning of the study period, when DES were first introduced, the majority of stents used were bare metal. At the end of the study, the vast majority of stents — over 90 percent — were DES. This gave us the opportunity to compare a large number of similar types of patients who received either BMS or DES. This is different from studies in other countries where the use of stents and particularly DES might be more restricted. The other advantage was that in Massachusetts, follow up of all patients undergoing an angioplasty with stents is mandatory, so we had a comprehensive dataset, which is very important when you want to look at rare adverse events. Finally, we included stents placed for any indication, so that we would really represent the spectrum of what is actually being done in real practice.

What were your findings? Were any of the conclusions surprising?
The purpose of this study was to determine whether there was an increase in the rates of either MI or death associated with DES compared to BMS over the long-term, out to two years. We were surprised to find that there was not a difference. In fact, there was actually a reduction in the rates of death and MI with DES compared to BMS. We also found that the rates of restenosis were reduced — similar to what we have seen with the randomized trials — and maintained out to two years. The other conclusion that was reassuring was that over the entire two-year period the benefit that we saw was consistent, without any crossing of the event curves to suggest a tradeoff in risks over time.

Can you comment on the use of dual antiplatelet therapy during the time periods covered by this analysis?
The time period that we looked at coincided with the introduction of DES in April 2003. At that time, the recommendations for dual-antiplatelet therapy were to use aspirin indefinitely and clopidogrel for three months for sirolimus-eluting stents and for six months for paclitaxel-eluting stents. This is important to place this study in context, as these recommendations are shorter than what the current DES guidelines suggest, which is 12 months.

Has your involvement with this project and its findings changed your views of DES or BMS safety?
I am reassured that this study demonstrated that there is not an adverse effect associated with drug-eluting stents. Before we did this study, I still had concerns regarding whether the randomized trials were large enough to detect an increase in the rate of mortality or MI. But after having conducted this study of almost 11,000 matched patients and being surprised to find lower rates of death and MI in these DES patients, I am reassured that these stents appear to be safe — at least out to two years of follow up.

What are your plans going forward in regards to this database?
There are several interesting questions going forward. As I mentioned, all patients who received a DES or BMS were eligible for this registry and many patients treated in our study were high risk because of either co-morbid conditions or their acute presentation. It is difficult to know how to best treat these patients, as they are not usually included in randomized trials. I think the Massachusetts data might be really helpful to see if the safety of DES holds up in higher risk groups. I also think it will be important to continue to follow these patients beyond two years to see if the findings are consistent.

Sponsored and prepared by Boston Scientific Corporation