The everolimus-eluting stent (EES) was as effective as the sirolimus-eluting stent (SES) in treating patients with total coronary occlusions, according to the results of a randomized trial published online Feb. 12 in Circulation: Cardiovascular Interventions.
Between 18 and 20 percent of patients who undergo coronary angiography have total coronary occlusions (TCO), and these patients often develop restenosis and reocclusion even when the initial treatment achieves recanalization. Although SES have been tested against bare metal stents in clinical trials and have been shown to achieve positive results, there had been no comparison of SES to EES specifically in TCO patients in a randomized clinical trial.
Raul Moreno, MD, of Hospital Universitario La Paz in Madrid, and colleagues designed the CIBELES (Coronary Occlusion treated by EveroLimus-Eluting Stent) trial to investigate whether the EES was inferior to SES in treating TCO patients. In a randomized, controlled, double-blind multicenter trial in Spain and Portugal, the researchers enrolled 207 patients with angina, silent ischemia or viable myocardium and TCO of estimated duration greater than two weeks.
Exclusion criteria included acute MI in the target area within two weeks before enrollment, lesions not successfully crossed and dilated with balloon angioplasty, lesions previously treated percutaneously, not suitable for treatment with 2.25mm to 3.5 mm coronary stents, patients unwilling to undergo angiographic follow-up, contraindications for dual-antiplatelet therapy, chronic renal failure and noncardiac disease rendering life expectancy to less than one year.
The researchers enrolled patients between Nov. 17, 2007 and September 2010. The primary endpoint was in-stent late loss, defined as the difference between minimum lumen diameter at the stent borders immediately after implantation and at nine-month angiographic follow-up. Noninferiority was defined as in-stent late loss less than or equal to 20 mm. Secondary endpoints were death, MI, new target vessel revascularization, binary angiographic restenosis, vessel reocclusion and in-segment late loss at nine months.
There were no statistically significant differences in the characteristics of the two groups of patients except that prior PCI was more prevalent in the SES group. The estimated time since occlusion was greater than three months in 80 percent of the patients, with no differences between the two groups. One SES patient had a coronary perforation and four had severe coronary dissections during the procedure; five EES patients had severe coronary dissections during the procedure. Two patients in each group had unsuccessful stent implantations, resulting in insufficient final distal flow.
During the 12 months of follow-up, 15.9 percent of SES patients and 11.1 percent of patients in the EES group experienced major adverse cardiac events, there were two deaths in the SES group and one in the EES group. Three SES patients experienced MI; there were no MIs in the EES group. New revascularization of the target vessel occurred in 20 patients, 11 in the SES group and 9 in the EES group; target lesion revascularization rate was 7.5 percent in the SES group and 6 percent in the EES group. The cumulative rate of stent thrombosis at 12 months was 3 percent in the SES group; none of the EES patients experienced stent thrombosis.
Angiographically, in-stent late loss in the SES patients was 0.29 mm compared with 0.13 mm in the EES group, so the noninferiority endpoint was reached. Binary restenosis occurred in 10.8 percent of the SES patients and 9.1 percent of the EES patients, and vessel reocclusion occurred in 3.2 percent and 1.1 percent, respectively.
The researchers noted that in-stent late loss was lower in the EES patients but not to a statistically significant degree. There also were no statistically significant differences in clinical or angiographic outcomes between the two groups, although numerically the SES group experienced more adverse clinical events.
The authors emphasized that “no definitive or probable stent thrombosis occurred in patients allocated to EES, in comparison with three allocated to SES.” However, they also acknowledged that their study was not sufficiently powered to draw a conclusion about the safety of SES.
As a further limitation of their study, they noted that they included patients with estimated TCO durations of as little as two weeks, although “true TCO are those with an estimated time since occlusion of greater than three months.” They contended inclusion of such patients was justified because in TCO estimated duration has an impact of probable success of recanalization rather than on risk of restenosis, and noted that several other randomized trials had used the same criterion.