Download this article's Factoid in PDF (& PPT for Gold Subscribers)

Among next-generation drug-eluting stents (DES), those that elute everolimus are more effective at reducing stent thrombosis and target lesion revascularization (TLR) at 1 year than those that release zotarolimus, according to a Korean registry published in the September 2012 issue of the Journal of the American College of Cardiology: Cardiovascular Interventions. However, both devices offer similar levels of protection against nonfatal myocardial infarction (MI) and death.

In the prospective, multicenter Korea Acute Myocardial Infarction Registry (KAMIR), Seung-Woon Rha, MD, of the Korea University Guro Hospital (Seoul, Korea) and colleagues examined safety and efficacy outcomes of 3,309 AMI patients treated with Endeavor Sprint zotarolimus-eluting stents (ZES; Medtronic CardioVascular; Santa Rosa, CA) or Xience V everolimus-eluting stents (EES; Abbott Vascular, Santa Clara, CA). Slightly more than 60% of patients presented with STEMI.

Stent Thrombosis Lower with EES

In-hospital and 1-year death rates were significantly lower for EES patients when considering the entire cohort.

When the investigators used propensity score matching to adjust for baseline differences in clinical and angiographic characteristics between the 2 groups (n = 1,343 pairs), however, the mortality difference disappeared. Both devices showed similar in-hospital mortality rates, whether cardiac (4.6% ZES and 4.2% EES; P = 0.572) or all-cause (5.0% ZES and 4.4% EES; P = 0.465).

At 1 year, the propensity analysis found no disparities in mortality or recurrent MI between ZES and EES. Other 1-year outcomes significantly favored EES, including target lesion failure (TLF; composite of cardiac death, recurrent nonfatal MI, and TLR), MACE (composite of total death, nonfatal recurrent MI, and TVR), and Academic Research Consortium definite or probable stent thrombosis. There was also a trend toward reduced TLR with EES vs. ZES (table 1).

Table 1. Propensity-Score Matched Cohort: One-Year Outcomes

In the matched cohort, EES use was an independent predictor of TLR (HR 0.53; 95% CI 0.28-1.00; P = 0.050), TLF (HR 0.72; 95% CI 0.54-0.96; P = 0.023), MACE (HR 0.70; 95% CI 0.55-0.90; P = 0.001), and definite/probable stent thrombosis (HR 0.18; 95% CI 0.06-0.52; P = 0.002).

Study Backs DES for AMI

David E. Kandzari, MD, of the Piedmont Heart Institute (Atlanta, GA), commented in an e-mail communication with TCTMD, “These data add to a growing body of literature that supports the safety of DES in the treatment of patients with MI.”

Despite positive findings from trials of first-generation devices, including TYPHOON and HORIZONS-AMI, he said, “the AMI indication has remained one in which skepticism and uncertainty have limited more widespread treatment with DES.” Dr. Kandzari reported that this is particularly true for STEMI patients who, compared with those who have less complex disease, experience “relatively higher rates of stent thrombosis and somewhat lower rates of TLR—the former attributed to underexpansion and malapposition of stents in a thrombotic milieu, and the latter postulated to be related to less atherosclerotic disease burden.”

Relevance for US Patients Unclear

In an e-mail communication, Dr. Rha told TCTMD that, as far as he knew, KAMIR represents the largest assessment of safety and efficacy of newer generation DES in AMI patients. Though conducted solely in an Asian population, “I think our results can be similarly applied to Americans,” he added, noting that typically the same stents are used in Korea as in the United States.

But Dr. Kandzari pointed out that differences in outcomes do exist between the 2 regions.

Previous US-based studies of DES in STEMI have produced stent thrombosis rates reaching up to 4% at 1 year, he said. The “lower than average rates [observed in KAMIR] are consistent with prior trials from Asia in non-AMI indications. Although the exact reasons for such disparity are unknown, it is noteworthy that nearly 30% of patients [here] were treated with cilostazol; whether this therapy, in combination with aspirin and a thienopyridine, further improves outcomes is an issue for further study,” Dr. Kandzari explained.

He concluded: “Short of a wide-scale randomized trial, these results do not establish EES as standard-of-care in AMI, but the data do add to increasing similar, mostly nonrandomized reports. . . . As the most commonly used stent worldwide, it is reassuring to learn that EES are at least as safe and effective as alternative DES.”

Related Stories:

• Meta-Analysis: Cobalt-Chromium EES Cut Stent Thrombosis Compared with BMS, Other DES 
• Stent Thrombosis Risk Lower with Xience vs. First-Generation DES
• Meta-analysis: Everolimus-Eluting Stents Reduce Thrombosis vs. Other DES