Home > Interventional Cardiology > ABSORB II 3 year Outcome

ABSORB II 3 year Outcome

Serruys et al report the 3 year outcome of the ABSORB II trial. The bioresorbable scaffold had higher device related outcomes and was similar with respect to patient related outcomes. Late loss was significantly lower in the EES.

The editorial is available here.

Abstract

Background

No medium-term data are available on the random comparison between everolimus-eluting
bioresorbable vascular scaff olds and everolimus-eluting metallic stents. The study aims to demonstrate two
mechanistic properties of the bioresorbable scaffold: increase in luminal dimensions as a result of recovered
vasomotion of the scaffolded vessel. Vasomotion was not improved with the scaffold.

Methods

The ABSORB II trial is a prospective, randomised, active-controlled, single-blind, parallel two-group,
multicentre clinical trial. We enrolled eligible patients aged 18–85 years with evidence of myocardial ischaemia and
one or two de-novo native lesions in different epicardial vessels. We randomly assigned patients (2:1) to receive
treatment with an everolimus-eluting bioresorbable scaffold (Absorb; Abbott Vascular, Santa Clara, CA, USA) or
treatment with an everolimus-eluting metallic stent (Xience; Abbott Vascular, Santa Clara, CA, USA). Randomisation
was stratifi ed by diabetes status and number of planned target lesions. At 3 year follow-up, the primary endpoint was
superiority of the Absorb bioresorbable scaffold versus the Xience metallic stent in angiographic vasomotor reactivity
after administration of intracoronary nitrate. The co-primary endpoint is the non-inferiority of angiographic late
luminal loss. For the endpoint of vasomotion, the comparison was tested using a two-sided t test. For the endpoint of
late luminal loss, non-inferiority was tested using a one-sided asymptotic test, against a non-inferiority margin of
0·14 mm. The trial is registered at ClinicalTrials.gov, number NCT01425281.

Findings

Between Nov 28, 2011, and June 4, 2013, we enrolled 501 patients and randomly assigned them to the Absorb
group (335 patients, 364 lesions) or the Xience group (166 patients, 182 lesions). The vasomotor reactivity at 3 years
was not statistically different (Absorb group 0·047 mm [SD 0·109] vs Xience group 0·056 mm [0·117]; p superiority=0·49),
whereas the late luminal loss was larger in the Absorb group than in the Xience group (0·37 mm [0·45] vs
0·25 mm [0·25]; p non-inferiority=0·78). This difference in luminal dimension was confirmed by intravascular ultrasound
assessment of the minimum lumen area (4·32 mm² [SD 1·48] vs 5·38 mm² [1·51]; p<0·0001). The secondary
endpoints of patient-oriented composite endpoint, Seattle Angina Questionnaire score, and exercise testing were not
statistically different in both groups. However, a device-oriented composite endpoint was significantly different
between the Absorb group and the Xience group (10% vs 5%, hazard ratio 2·17 [95% CI 1·01–4·70]; log-rank
test p=0·0425), mainly driven by target vessel myocardial infarction (6% vs 1%; p=0·0108), including peri-procedural
myocardial infarction (4% vs 1%; p=0·16).

Interpretation

The trial did not meet its co-primary endpoints of superior vasomotor reactivity and non-inferior late
luminal loss for the Absorb bioresorbable scaffold with respect to the metallic stent, which was found to have
significantly lower late luminal loss than the Absorb scaffold. A higher rate of device-oriented composite endpoint due
to target vessel myocardial infarction, including peri-procedural myocardial infarction, was observed in the Absorb
group. The patient-oriented composite endpoint, anginal status, and exercise testing, were not statistically different
between both devices at 3 years. Future studies should investigate the clinical impact of accurate intravascular imaging
in sizing the device and in optimising the scaffold implantation. The benefit and need for prolonged dual antiplatelet
therapy after bioresorbable scaffold implantation could also become a topic for future clinical research.

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