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New ABSORB data provide insights into BVS
Patients who received a bioresorbable vascular scaffold had similar event rates to those who received an everolimus-eluting coronary stent system, although some data show that rates are slightly higher for BVS, according to data from three studies presented at TCT 2017.
The FDA has updated its March letter to health care providers to reflect 3-year follow-up data from the ABSORB III trial, which found that device-related clinical events occurred between 1 and 3 years in patients assigned a BVS (Absorb, Abbott Vascular) or an EES (Xience, Abbott Vascular), with more events occurring in the BVS group.
3 -year outcomes in ABSORB III
Stephen G. Ellis, MD, director of interventional cardiology and senior academic officer of the Heart & Vascular Institute at Cleveland Clinic, and colleagues reviewed 3-year follow-up data from 2,008 patients assigned to an EES (n = 686) or a BVS (n = 1,322).
Patients met criteria such as evidence of myocardial ischemia, no elevation of creatine kinase-MB, one or two de novo target lesions in up to two coronary arteries and right ventricular diameter between 2.5 mm and 3.75 mm.
At 3 years, target lesion failure was significantly higher in patients in the BVS group (13.4%) compared with the EES group (10.4%; HR = 1.31; 95% CI, 0.99-1.73).
There was no difference between all-cause death and cardiac death in both groups.
The incidence of all MIs was higher in the BVS group (10.2% vs. 7.6%) than the EES group, as was the incidence of target-vessel MI (8.6% vs. 5.9%).
Device thrombosis was significantly higher in patients assigned BVS (2.3%) compared with the EES group (0.7%; HR = 3.12; 95% CI, 1.21-8.05).
Between 2 and 3 years, there was little difference in outcomes between the two groups.
A landmark analysis compared patients with a RV diameter less than 2.25 mm and those with a diameter greater than 2.25 mm. At 1 year, device-related thrombosis occurred in 4.6% of patients with a diameter less than 2.25 mm who were assigned BVS and 1.5% of those assigned EES (P = .12), but there was little difference at 3 years (0.4% and 0%, respectively; P = .47). At 1 year, there was less of a difference in patients with a diameter of at least 2.25 mm who were assigned BVS vs. EES (0.8% and 0.5%, respectively; P = .52). The occurrence of device-related thrombosis was 0.9% for the BVS group and 0% for the EES group at 3 years (P = .03).
“Longer-term clinical follow-up is necessary to determine whether more normal coronary structure and function after scaffold bioresorption will eventually result in a favorable late net safety and efficacy profile of BVS compared to permanent metallic EES,” Ellis said during a press conference.
“We tend to believe that improved platforms to make scaffold implantation as user friendly as metal stent implantation, as applied not only by the most highly experienced operators but also the average operator, will be required to match the very high bar already established by metal DES,” Spencer B. King III, MD, MACC, FSCAI, FESC, and Bill D. Gogas, MD, PhD, from the cardiology division at Emory University School of Medicine, wrote in a related editorial. “The reason to persevere is not because of any expectation that scaffolds can beat metal stents in the intermediate terms, but the concern that metal stents will begin to produce significant adverse events many years after implantation.”
ABSORB II results
Bernard R. Chevalier, MD, from the Institut Cardiovasculaire Paris Sud in Massy, France, and colleagues analyzed 4-year follow-up data from 501 patients who were assigned to a BVS (n = 335) or EES (n = 166).
The coprimary endpoints were vasomotion assessed by change in mean lumen diameter, minimum lumen diameter and postprocedure post-nitrate at 36 months.
At 4 years, 86% of patients in the BVS group and 84% of the EES group were still participating in the trial.
The device-oriented composite endpoint, which was defined as target-vessel MI, cardiac death and clinically indicated target lesion revascularization, occurred in 11.1% of patients assigned BVS vs. 5.6% assigned EES (HR = 2.04; 95% CI, 0.98-4.24).
The incidence of the patient-oriented composite endpoint, which was all instances of MI, death and revascularization, was 24.9% in the EES group and 22.9% in the BVS group (HR = 0.9; 95% CI, 0.61-1.33).
Each group had one cardiac death, and one MI occurred in the BVS group. TLR occurred in two patients assigned BVS vs. no patients assigned EES.
Definite or probable scaffold or stent thrombosis occurred in 2.8% of those in the BVS group, with none occurring in the EES group. Thrombosis did not occur in both groups between 3 and 4 years.
At 4 years, 84.4% of patients from the BVS group were on aspirin compared with 81.3% of the EES group (P = .3794). Dual antiplatelet therapy was utilized in 25.9% of patients assigned BVS and 21.1% of patients assigned EES (P = .2372).
“The exploratory observations presented in this report are hypothesis-generating and need to be confirmed in larger randomized trials such as ABSORB III and ABSORB IV,” Chevalier said.
30-day outcomes in ABSORB IV
Gregg W. Stone, MD, professor of medicine at Columbia University Medical Center and director of cardiovascular research and education at the Center for Interventional Vascular Therapy at NewYork-Presbyterian Hospital, and colleagues analyzed 30-day follow-up data from 2,604 patients with stable ischemic heart disease or ACS, one to three target lesions and a right vessel diameter between 2.5 mm and 3.75 mm. Patients were assigned to BVS (n = 1,296) or EES (n = 1,308).
The primary endpoint was TLF at 30 days.
In the intention-to-treat group, 5% of patients assigned BVS and 3.7% assigned EES had TLF with a noninferiority margin of 2.9%. In the as-treated group, 4.6% of the BVS group and 3.7% in the EES group had TLF with a noninferiority margin of 2.9%.
Endpoints were infrequent in both groups except for non-periprocedural MI, which occurred in 0.8% of patients assigned BVS and 0.2% assigned EES (P = .049). Ischemia-driven TLR was more prevalent in the BVS group (1%) compared with the EES group (0.2%; P = .01).
Device thrombosis was seen in 0.6% of patients in the BVS group and 0.2% of those in the EES group (HR = 4.05; 95% CI, 0.86-19.07). When comparing patients who were similar to those in the ABSORB III trial, the incidence of device thrombosis was 0.4% in the BVS group and 0% in the EES group.
“There’s no interaction P values here, but by getting rid of the very small vessels, we improved outcomes,” Stone said during the press conference.
Although the endpoint was technically met, it was met barely. Both devices can benefit from avoiding small vessels and implementing good techniques, according to the presentation.
More research is needed to justify the use of a BVS in addition to longer-term follow-up, as there may be some explanations on how long-term outcomes can benefit from the absence of permanent metallic stents.
“These data, which are largely consistent with those from earlier ABSORB trials, emphasize the need for advancements in device technology and standardized technique to further improve the outcome of BVS,” he said.
As Cardiology Today’s Intervention has previously reported, Abbott ceased sales of the BVS in September due to low commercial sales.
“Not just Abbott, but all the companies are ... developing similar products and are looking to see what these longer-term results look like because it could definitely impact the decision on whether we come back with a second-generation device that maybe addresses some of the challenges that we had with the first-generation device,” Chuck Simonton, MD, chief medical officer and divisional vice president of global medical affairs for Abbott, said in an interview with Cardiology Today’s Intervention. – by Darlene Dobkowski
References:
Chevalier BR, et al. Late-Breaking Clinical Trials 2. Presented at: TCT Scientific Symposium; Oct. 29-Nov. 2, 2017; Denver.
Ellis SG, et al. Late-Breaking Clinical Trials 2. Presented at: TCT Scientific Symposium; Oct. 29-Nov. 2, 2017; Denver.
Stone GW, et al. Late-Breaking Clinical Trials 2. Presented at: TCT Scientific Symposium; Oct. 29-Nov. 2, 2017; Denver.
King SB III, et al. J Am Coll Cardiol. 2017;doi:10.1016/j.jacc.2017.10.009.
Disclosures: The ABSORB trials were funded by Abbott Vascular. Ellis reports he receives consultant and research funding from Abbott Vascular, Boston Scientific and Medtronic. Stone reports he is the chairman of the ABSORB global clinical trial program and is a consultant for Reva. Chevalier reports he served as a consultant for Abbott Vascular and is currently a consultant for Biotronik, Colibri, Cordis, Medtronic and Terumo. King and Gogas report no relevant financial disclosures.