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Biodegradable stents, bioresorbable scaffolds reduce risk for TLF
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MUNICH — Results from three studies presented at the European Society of Cardiology Congress found that biodegradable stents and bioresorbable scaffolds are effective for reducing the risk for target lesion failure.
BIOSCIENCE
An ultrathin-strut, biodegradable-polymer sirolimus-eluting stent and a thin-strut, durable-polymer everolimus-eluting stent had comparable rates of TLF at 5 years, according to data from the BIOSCIENCE trial presented at the European Society of Cardiology Congress. Results from the trial were also simultaneously published in The Lancet.
Thomas Pilgrim, MD, chief physician of invasive cardiology and head of the cardiac values department at Inselspital at Universitätsspital Bern in Germany, and colleagues analyzed data from 2,119 patients with stable CAD or ACS who were assigned an SES (Orsiro, Biotronik; n = 1,063; median age, 66 years; 77% men) or an EES (Xience, Abbott; n = 1,056; median age, 66 years; 77% men) between February 2012 and May 2013.
“The Orsiro biodegradable-polymer sirolimus-eluting stent combines an ultrathin-strut cobalt-chromium stent platform with a biodegradable poly-L-lactic acid polymer that elutes sirolimus over the course of 12 to 14 weeks and degrades completely within 1 to 2 years,” Pilgrim said during the presentation. “On the other hand, the Xience durable-polymer everolimus-eluting stent is also based on the cobalt-chromium stent platform, but with a strut thickness of 81 µm and the durable-polymer eluting everolimus.”
Follow-up was conducted for 5 years. The primary endpoint was TLF, defined as a composite of target vessel MI, cardiac death and clinically indicated target lesion revascularization.
Dual antiplatelet therapy adherence in the SES and EES groups was high within the first year after stent implantation (84% vs. 82%, respectively), which decreased to 15% in both groups at 2 years and 8% in both groups at 5 years, although the differences between groups were not statistically significant.
The cumulative incidence of TLF at 1 year was 6.7% in both treatment arms (RR = 0.99; 95% CI, 0.71-1.38; P for noninferiority = .0004). At 5 years, patients assigned SES had an incidence rate of 20.2% vs. 18.8% in patients assigned EES (RR = 1.07; 95% CI, 0.88-1.31).
Cardiac death occurred in 8.6% of patients in the SES group at 5 years and 7.5% of those in the EES group (RR = 1.1; 95% CI, 0.8-1.5). More patients in the EES group had target vessel MI compared with the SES group (7.1% vs. 6.3%; RR = 0.91; 95% CI, 0.65-1.28). Clinically driven TLR occurred in 10.8% of patients assigned SES and 10% of those assigned EES (RR = 1.1; 95% CI, 0.83-1.45).
“There were no significant differences between the two treatment arms in any of the individual components of the primary endpoint,” Pilgrim said.
Rates of definite stent thrombosis at 1 year were numerically higher in the SES group compared with the EES group (0.9% vs. 0.4%; RR = 2.25; 95% CI, 0.69-7.32). The rate between 1 year and 5 years was lower in patients assigned SES vs. EES (0.7% vs. 1.2%; RR = 0.61; 95% CI, 0.24-1.54).
At 5 years, all-cause mortality was significantly higher in patients assigned SES compared with EES (14.1% vs. 10.3%; HR = 1.36; 95% CI, 1.06-1.75), driven by non-CV deaths. This was also seen in the rate of non-CV death (5.3% vs. 2.8%, respectively; HR = 1.93; 95% CI, 1.22-3.06).
“In particular, higher rates were related to cancer in patients treated with the Orsiro stent,” Pilgrim said.
There were no significant differences between the two groups regarding cardiac death and vascular noncardiac death.
In a stratified analysis of the primary endpoint, there were consistent findings in subgroups, including diabetes, ACS, STEMI, off-label use and use in patients with small coronary arteries.
Researchers also performed a meta-analysis of five trials that compared the same SES and EES assessed in the trial, and there was a 23% reduction of MI in patients who were treated with SES vs. EES (RR = 0.77; 95% CI, 0.63-0.95).
“Lower rates of myocardial infarction in a meta-analysis of biodegradable-polymer sirolimus-eluting stents vs. durable-polymer everolimus-eluting stents may be related to the ultrathin-strut thickness,” Pilgrim said.
“These considerations [of factors that affect event rates] and the long-term results of BIOSCIENCE suggest that it is desirable to obtain outcome data for novel coronary stents from more than one randomized clinical trial,” Clemens von Birgelen, MD, PhD, FSCAI, FESC, professor of cardiology at the University of Twente in Enschede, the Netherlands, and co-director of the department of cardiology at Thoraxcentrum Twente at Medisch Spectrum Twente in Enschede, the Netherlands, and Paolo Zocca, research fellow of interventional cardiology at Medisch Spectrum Twente, wrote in a related editorial. “Ideally, these trials should originate from different countries so as to increase diversity in study populations. Ultimately, late follow-up of clinical trials might be a matter of life or death.”
ISAR-ABSORB MI
Bioresorbable scaffolds were noninferior to EES regarding percentage diameter stenosis in patients who underwent PCI for acute MI, according to results from the ISAR-ABSORB MI trial presented at the European Society of Cardiology Congress.
In the ISAR-ABSORB MI trial, Robert Byrne, PhD, senior physician in the department of cardiovascular diseases at German Heart Centre of the State of Bavaria in Munich, and colleagues analyzed data from 262 patients with STEMI or non-STEMI if accompanied by a thrombosis visual at angiography with de novo lesions in native vessels or coronary bypass grafts and a right ventricle diameter between 2.5 mm and 3.9 mm.
Patients were assigned to treatment with a bioresorbable scaffold (Absorb, Abbott Vascular; n = 173; mean age, 62 years; 20% women) or an EES (Xience; n = 89; mean age, 63 years; 27% women). Five patients in the bioresorbable scaffold group and two patients in the EES group did not receive the assigned device.
The primary endpoint was the percentage diameter stenosis at coronary angiography between 6 and 8 months after the intervention. Patients underwent angiographic follow-up at 6 months and clinical follow-up at 1 year.
During follow-up, the cumulative rate of the primary endpoint was 24.6% for the bioresorbable scaffold group vs. 27.3% for the EES group (mean difference = –2.7; 95% CI, –6 to 0.7; P for noninferiority < .001). The mean difference in a sensitivity analysis was –1.9% with imputation for missing data (P for noninferiority < .001).
In the subgroup analysis for the primary endpoint, there was no evidence of interaction with the treatment effect except for presentation diagnosis. Patients with STEMI had a more favorable result with the bioresorbable scaffold compared with those with non-STEMI (P for interaction = .004).
Late lumen loss was 0.1 mm in both groups (mean difference = 0; 95% CI, –0.11 to 0.12). The rate of TLR was 4.8% in patients assigned bioresorbable scaffold vs. 5.7% in those assigned EES (HR = 0.84; 95% CI, 0.27-2.57). The rate of CV death and MI was similar in the bioresorbable scaffold group and the EES group (4.1% vs. 4.5%, respectively; HR = 0.9; 95% CI, 0.26-3.06). Patients assigned the bioresorbable scaffold had a rate of definite or probable stent thrombosis of 1.7% compared with 2.3% in those assigned EES (HR = 0.76; 95% CI, 0.13-4.56).
Both groups also had similar rates of the device-oriented composite endpoint (HR = 1.02; 95% CI, 0.39-2.78) and the patient-oriented composite endpoint (HR = 0.9; 95% CI, 0.26-3.06).
“Acute myocardial infarction with STEMI in particular may possibly represent a clinical setting in which further assessment of bioresorbable scaffolds is warranted,” Byrne said during the presentation.
European ABSORB Consortium
Researchers from the European ABSORB Consortium analyzed 12-month follow-up data from 10,312 patients (mean age, 58 years; 79% men) from five European registries who received the Absorb scaffold.
“The [European ABSORB Consortium] is the largest registry of [bioresorbable scaffolds] globally and allows accurate assessment of low-frequency clinical outcome parameters including device thrombosis and restenosis,” Holger M. Nef, MD, associate professor of internal medicine at University of Giessen in Germany, said during the presentation.
Follow-up was conducted through telephone interviews and was completed in 95.5% of patients.
Of these patients, 28.1% had stable angina, 58.3% had ACS and 34.2% had STEMI.
At 12 months, the rates of clinical outcomes were as follows: mortality, 1.2%; cardiac death, 0.6%; any MI, 2.7%; target vessel MI, 1.8%; TLR, 2.6%; and target vessel revascularization, 3.2%. TLF, which was defined as a composite of cardiac death, target vessel MI and TLR, occurred in 3.6% of patients. Target vessel failure, defined as cardiac death, target vessel MI and TLR, occurred in 4.5% of patients in the study.
Scaffold thrombosis, both definite and probable, was seen in 1.6% of patients (0.3% within 24 hours, 0.6% between 24 hours and 30 days, 0.6% after 30 days).
A landmark analysis at 12 months showed that at 30 days, the rate of definite or probable device thrombosis was 0.94% and the rate of TLF was 1.3%. Between 1 month and 12 months, the rate of scaffold thrombosis was 0.58% and the rate of TLF was 2.15%.
Independent predictors of scaffold thrombosis were the absence of predilatation and presence of bifurcation. For TLF, the independent predictors were bifurcation and no dual antiplatelet therapy.
Researchers compared patients who had bioresorbable scaffolds implanted before 2015 and after 2015.
“The specific cutoff was chosen because the [instruction for use] was changed in November 2014,” Nef said during the presentation.
The composite endpoint of TLF (4.2% vs. 3.2%) and TVF (5% vs. 4.1%) was significantly reduced after the instruction was changed. Scaffold thrombosis slightly decreased from 1.8% to 1.4% and was not statistically significant.
“The [European ABSORB Consortium] demonstrates favorable real-world clinical outcome data for [bioresorbable scaffolds], with TLF comparable to data available for second-generation DES registries; nevertheless, the rate of [scaffold thrombosis] remains high,” Nef said. “Clinical outcome rate after treatment with [bioresorbable scaffolds] depends on implantation protocol and might be even better with newer iterations of [bioresorbable scaffolds].” – by Darlene Dobkowski
References:
Pilgrim T, et al.
Byrne R, et al.
Nef HM, et al. Late-Breaking Science in Interventional Cardiology 2. All presented at: European Society of Cardiology Congress; Aug. 25-29, 2018; Munich.
Pilgrim T, et al. Lancet. 2018;doi:10.1016/S0140-6736(18)31715-X.
von Birgelen C, et al. Lancet. 2018;doi:10.1016/S0140-6736(18)31860-9.
Disclosures: The BIOSCIENCE trial was funded by the Clinical Trials Unit of the University of Bern and Biotronik. The ISAR-ABSORB MI trial was funded in part by a grant from Abbott Vascular. Byrne reports he received lecture fees/honoraria from B. Braun Melsungen AG, Biotronik, Boston Scientific and Micell Technologies, and research contracts from Boston Scientific and Celonova. Nef reports he received research grants and speaker’s fees from Abbott Vascular and Elixir Medical. Pilgrim reports he received research grants to his institution from Biotronik, Boston Scientific and Edwards Lifesciences, and speaker fees from Biotronik and Boston Scientific. Von Birgelen reports his research department received institutional research grants from Abbott Vascular, Biotronik, Boston Scientific and Medtronic, and was an unpaid consultant for Abbott Vascular, Biotronik and Medtronic. Zocca reports no relevant financial disclosures.