STOCKHOLM — Four-fifths of the more than 3,000 patients who received drug-eluting coronary stents at one U.S. medical center fell outside the entry criteria used in the major trials of such stents.
And patients with risk factors that placed them outside of the trial criteria had, in general, much worse outcomes than did patients who met the trial criteria. For example, patients with two high-risk factors that were not included in the original trials had an 11.3% rate of major adverse cardiac events (MACE) during the first year after receiving drug-eluting stents, double the 5.7% rate seen in patients who fell within the trial criteria, Gregory J. Mishkel, M.D., reported in a poster at the annual congress of the European Society of Cardiology. The cost of hospitalization also rose as the number of risk factors rose.
The findings raised the question of whether the use of drug-eluting stents is preferable to coronary bypass surgery in patients with several risk factors. “In patients with three or more risk factors, bypass remains a viable option,” Dr. Mishkel said in an interview. The results from the randomized, controlled trials of drug-eluting coronary stents “do not directly translate to the real world,” because in the real world patients have more risk factors, he added.
The study reviewed all 3,059 patients who received a drug-eluting coronary stent at St. John's Hospital in Springfield, Ill., during May 2003-December 2004. Among this group, 613 (20%) met enrollment criteria for either the RAVEL or SIRIUS trials, which were the major studies to test the safety and efficacy of sirolimus-eluting coronary stents (Cypher), or the TAXUS studies, which were the major studies to test paclitaxel-eluting stents (Taxus). All of the other patients had at least one factor that would have excluded them from these trials. These risk factors included multilesion stenting, a bifurcated lesion, and a vessel diameter of less than 2.5 mm. More than 10% of the St. John's patients had at least four high-risk factors.
The patients with no risk factors had the lowest incidence of MACE during the first year following stent placement. The MACE rate increased as the number of risk factors increased, rising to 8.2% in patients with any single risk factor, 13.7% in those with three risk factors, 13.9% in patients with four risk factors, and 18.6% in those with five or more risk factors, reported Dr. Mishkel, codirector of the coronary catheterization laboratory at St. John's Hospital.
Average hospitalization costs also increased as the number of risk factors accumulated. Patients with no risk factors had an average cost of $9,905. Those with two risk factors had their average costs jump by 26%. Patients with four risk factors had their average costs rise by 70%, and for patients with five or more risk factors the average cost nearly doubled.
A multivariate analysis of the risk factors found that placement of a drug-eluting stent in a previously dilated coronary artery was associated with a 2.3-fold increase in the MACE rate, the greatest impact of any factor on the MACE rate. Other risks linked with jumps in the MACE rate were age of more than 85 years, linked with a 2.1-fold rise in the MACE rate; presence of thrombus, linked with a 77% increase; and multilesion stenting, linked with a 58% rise. Coronary arteries wider than 2.5 mm had a 30% lower MACE rate, compared with narrower vessels.