EVENT Registry Analysis Supports Selective DES Use

August 15, 2011—The American Heart Association (AHA) announced that an analysis of data from the EVENT (Evaluation of Drug-Eluting Stents and Ischemic Events) registry to examine the clinical impact and cost-effectiveness of varying drug-eluting stents (DES) use rates in routine care was published by Lakshmi Venkitachalam, PhD, et al online ahead of print in Circulation. The background of the study is that although the benefits of DES for reducing restenosis after percutaneous coronary intervention are well established, the impact of alternative rates of DES use on population-level outcomes is unknown.

As detailed in Circulation, between 2004 and 2007, 10,144 patients undergoing percutaneous coronary intervention were enrolled in the EVENT registry at 55 centers in the United States. The investigators prospectively assessed clinical outcomes and cardiovascular-specific costs during 1-year follow-up. Use of DES decreased from 92% in 2004 to 2006 (liberal use era, n = 7,587) to 68% in 2007 (selective use era, n = 2,557; P < .001). One-year rates of death or myocardial infarction were similar in both eras.

The investigators found that during this time period, the incidence of target lesion revascularization (TLR) increased from 4.1% to 5.1%, an absolute increase of 1% (95% confidence interval, 0.1–1.9; P = .03), whereas total cardiovascular costs per patient decreased by $401 (95% confidence interval, 131–671; P = .004). The risk-adjusted incremental cost-effectiveness ratio for the liberal versus selective DES era was $16,000 per TLR event avoided, $27,000 per repeat revascularization avoided, and $433,000 per quality-adjusted life-year gained.

The investigators concluded that in this prospective registry a temporal reduction in DES use was associated with a small increase in TLR and a modest reduction in total cardiovascular costs. They stated that these findings suggest that although clinical outcomes are marginally better with unrestricted DES use, this approach represents a relatively inefficient use of health care resources relative to several common benchmarks for cost-effective care.

Commenting on the findings to the AHA, lead investigator David J. Cohen, MD, said, “The bottom line was that using drug-eluting stents in a relatively unselected way was only resulting in marginal improvement compared to more selective use.” Referring to the earlier years of broader use, he observed, “We were putting a lot more drug-eluting stents in and we benefited very few additional patients.”

According to the AHA, the investigators noted that several studies in late 2006 reported a higher risk of clotting, heart attacks, and deaths in patients with DES, causing the US Food and Drug Administration (FDA) to conduct an analysis of the problem. Dr. Cohen explained, “These concerns led to a stair-step reduction in the use of drug-eluting stents, which had expanded rapidly since their introduction in 2003. Because of the safety concerns, we were able to verify what many of us had suspected—that using drug-eluting stents in virtually all patients is not that efficient.”

Although Dr. Cohen believes the FDA concern was appropriate at the time, newer evidence with longer follow-up and more data has indicated that DES are safe. “Our current understanding is there is no real excess risk,” he said, noting that later risk of dangerous clots might be balanced by earlier benefits.

The AHA stated that the investigators found that when use of DES declined in 2007, the stents were more likely to be placed in patients who were at highest risk of restenosis, including younger patients with smaller vessels or with longer problem areas in the vessels being treated. Dr. Cohen stated, “Because we were selectively targeting the highest-risk patients, we were able to use far fewer drug-eluting stents while preserving the clinical benefit.”

The investigators noted that given the approximately 1 million angioplasty procedures performed in the United States, the $401 per patient average reduction of health care costs is magnified into hundreds of millions of dollars of savings each year. Dr. Cohen commented that policy makers should appreciate that more targeted use of DES produces comparable clinical outcomes at a lower cost. He added, “There are ways that we can enhance this treatment pattern through health care policies, professional guidelines, or appropriate use criteria.”

The AHA advised that the new analysis does not directly identify which patients are the best candidates for DES, but that other studies are currently underway using similar patient registries to answer these related questions. The analysis was also limited to 1 year, which is the time frame in which restenosis usually occurs.