NEW ORLEANS — Diabetic patients treated with drug-eluting stents showed impressive reductions in mortality, acute MI, and repeat revascularization during the subsequent 3 years compared with bare-metal stent recipients in a large real-world Massachusetts registry featuring mandatory reporting and follow-up.
The mortality benefit for drug-eluting stents (DES) relative to bare-metal stents (BMS) in this consecutive series of more than 5,000 diabetic patients was surprising. The study was conducted to address safety concerns that have arisen regarding DES in the last couple of years. It turned out that in a diabetic population, DES were not associated with increased hazard; indeed, the opposite proved true, Dr. Laura Mauri reported at the annual scientific sessions of the American Heart Association.
This is an important finding because diabetic patients now account for roughly one-third of all angioplasties performed in clinical practice. This is a population that tends to have very aggressive coronary disease with high rates of restenosis, MI, and cardiac death, both periprocedurally and long term, explained Dr. Mauri of Brigham and Women's Hospital and Harvard Medical School, Boston.
The Massachusetts Data Analysis Center Registry (Mass-DAC) includes all patients undergoing percutaneous coronary intervention at nonfederal hospitals statewide. During the 18-month study period beginning in April 2003, there were 3,341 diabetic patients who underwent DES-only PCI and 1,710 who received only BMS with subsequent complete 3-year follow-up data.
The unadjusted differences in 3-year mortality, MI, and target-vessel revascularization (TVR) were strikingly in favor of DES. However, because this was an observational study and the DES and BMS groups differed in key ways at baseline, the investigators performed a logistic regression propensity score-matched analysis involving 1,476 DES recipients and an equal number of BMS recipients matched according to 67 patient, procedural, and hospital variables. Clinical outcomes in the DES group remained significantly better. (See box.)
The mortality curves for the DES- and BMS-treated patients separated in the first month and stayed roughly parallel from the 6-month mark through the full 3 years of follow-up, showing the durability of the DES survival benefit, she noted.
Discussant David O. Williams said the clinical implication of the Massachusetts study is that DES are the preferred PCI option whenever possible in diabetic patients. “Probably the selection of a bare-metal stent over a drug-eluting stent will be based on a patient's inability to take dual antiplatelet therapy for a sustained period of time,” added Dr. Williams, professor of medicine at Brown University, Providence, R.I.
He noted that he and his coinvestigators in the National Heart, Lung, and Blood Institute Dynamic Registry recently reported a lower 1-year risk of TVR in 1,749 DES-treated diabetic participants than that of 817 in the BMS group. They also found a 43% reduction in the risk of death or MI with DES in non-insulin-treated diabetics, but no difference in the insulin-dependent patients (J. Am. Coll. Cardiol. Intv. 2008;1:139–47).
The randomized trials that led to regulatory approval of the DES have not shown mortality or MI benefits over BMS with several years' follow-up. That may be because the early trial participants had uncomplicated disease, Dr. Williams explained, adding that the benefits may show up only in higher-risk patients, such as those with diabetes.
Dr. Mauri speculated that the mortality reduction observed with DES in diabetic patients in the Massachusetts study was probably due to a combination of three factors. For one, it wasn't possible to adjust for the duration of dual antiplatelet therapy with aspirin and a thienopyridine, yet the DES-treated group was likely on dual antiplatelet therapy longer, since the standard regimen during the study period was 3–6 months for DES compared with 1 month for BMS.
Also, DES patients tended to have more complete revascularization, which may have reduced late coronary events. Finally, by preventing restenosis and thus avoiding the invasive procedures employed to treat restenosis, some periprocedural MIs and deaths were averted.
Roughly three-quarters of DES implanted in study participants were sirolimus eluting, since those stent types reached the U.S. marketplace earlier than did paclitaxel-eluting stents. No difference in the study end points was seen between the two DES types.
The study was funded by the Massachusetts Department of Public Health. Dr. Mauri has received honoraria from Abbott Vascular, Boston Scientific, Cordis, and Medtronic Vascular.
In a diabetic population, DES were not linked with increased hazard; indeed, the opposite proved true. DR. MAURI
The benefits of DES may show up only in higher-risk patients, such as those with diabetes. DR. WILLIAMS
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