CHICAGO — Two-year mortality was significantly lower with drug-eluting stents than with bare metal stents in a registry including every patient in Massachusetts who underwent percutaneous coronary intervention with stenting for acute MI during an 18-month period.
“Although our aim was to detect whether there was any signal of harm, we actually observed lower mortality at 2 years in patients treated with drug-eluting stents,” Dr. Laura Mauri reported at the annual meeting of the American College of Cardiology.
The study was undertaken because the use of drug-eluting stents (DES) in acute MI is fraught with controversy. The trials that led to marketing approval of DES excluded patients with MI. Subsequent randomized trials looking at DES in MI have been small and a year or less in duration. There has been widespread concern that late events—especially late stent thrombosis—might offset the early therapeutic advantages of DES.
The Massachusetts registry is well suited to shed light on the controversy as it is the largest in the United States, with longer follow-up than in any of the randomized trials. And while the registry is observational in nature, the results are more generalizable to real-world clinical practice than are randomized trials, with their numerous exclusions. The registry includes mandatory reporting of data on all patients by every practicing interventional cardiologist in the state, explained Dr. Mauri, an interventional cardiologist at Brigham and Women's Hospital and chief scientific officer at the Harvard Clinical Research Institute, Boston.
The 7,216 Massachusetts residents who underwent stenting for MI represented 40% of all patients undergoing percutaneous coronary intervention (PCI) during the study period. The unadjusted 2-year mortality rate was 9.0% in those who received a DES and 14.0% in those who got bare metal stents (BMS).
Because of selection bias—patients with more severe comorbidities were more likely to get BMS, while those with more complex coronary lesions tended to get DES—the investigators performed an analysis involving 2,629 pairs of stent-treated MI patients matched for clinical risk, hospital characteristics, and other factors. The 2-year risk-adjusted mortality rate was 10.6% in the DES recipients and 13.4% with BMS in the overall acute MI population, and 8.0% versus 11.7% for those with ST-segment elevation MI (STEMI). The target vessel revascularization rate was also significantly lower in the DES group, at 15.5%, compared with 20.8% with BMS.
Importantly, there was no evidence of a late increase in adverse events in the DES-treated patients out to 2 years. The Massachusetts cohort will be followed longer term in future reports, according to Dr. Mauri.
Discussant Dr. Bruce R. Brodie said his own involvement in a smaller registry of stenting for MI has convinced him there is an inherent selection bias that just can't be eliminated by statistical adjustments. He cited as an example an increased likelihood of poor compliance with dual-antiplatelet therapy and other key medications among BMS recipients.
“Should we be putting in drug-eluting stents in most non-STEMI and STEMI patients? I don't think we're quite ready to make that jump,” declared Dr. Brodie of Moses H. Cone Memorial Hospital, Greensboro, N.C.
He said he is particularly concerned about the potential for late stent thrombosis with DES beyond the 2-year mark caused by stent malapposition. STEMI patients are inherently among the highest-risk groups for stent thrombosis because of a tendency for stents to be undersized and underdeployed because of vasoconstriction and thrombus burden. In one study, the late malapposition rate was 25% with DES versus 5% with BMS, he noted.
Dr. William D. Knopf, chief operating officer at Atlanta's Piedmont Heart Institute, called the Massachusetts data “very encouraging” and predicted a resultant increase in the use of DES in MI.
The 2-year mortality rate was 9.0% in patients who received a DES and 14.0% in those who got BMS. DR. MAURI