By Laura Cowen
Postprocedural asymmetry following percutaneous coronary intervention (PCI) is associated with an increased risk of adverse clinical outcome, particularly in patients with suboptimal expansion, researchers report.
Multivariate analysis revealed that a postprocedural asymmetry index (AI) above 0.30 (based on criteria from the MUSIC study) was associated with a 3.43-fold increased risk of the device-oriented composite endpoint (DoCE) of cardiac death, myocardial infarction or ischaemia-driven target lesion revascularisation by coronary bypass graft or PCI.
This risk increased to 6.19-fold for patients with asymmetry and suboptimal stent expansion.
Although low event rates mean the results should be viewed as "hypothesis generating", Patrick Serruys (Imperial College London, UK) and co-authors suggest that "[p]ost-intervention AI >0.30 should be avoided to reduce asymmetry or eccentricity-related complication".
Using data from the ABSORB II trial, the researchers found that 1 year after treatment, there was no overall difference in the DoCE between the 308 patients with coronary artery stenosis who received a bioresorbable vascular scaffold (BVS) and the 162 who had a metallic everolimus-eluting stent (EES), at 5.2% versus 3.1%.
This was in spite of significantly higher rates of eccentricity (27.3 vs 4.5%) and asymmetry (62.1 vs 29.5%) and a significantly lower rate of optimal scaffold/stent expansion (8.0 vs 20.0%) with BVS versus EES.
However, when stratified by AI, the rate of DoCE was significantly higher in the asymmetric group (AI >0.30) than in the symmetric group (AI ≤0.30), at 6.9% versus 1.8%.
Further subgroup analysis suggested that the influence of asymmetric lumen on DoCE was significant in patients with a BVS, at a hazard ratio of 9.19 for DoCE in the asymmetric versus symmetric groups, but not in those given a metallic EES.
"This suggests that this parameter of AI could be useful for BVS implantation, but not for metallic EES implantation", say editorialists Myeong-Ki Hong and Jung-Sun Kim, from Yonsei University College of Medicine in Seoul, Korea.
Significantly higher rates of the DoCE were also observed among patients with eccentric lesions, compared with those with centric lesions, at 8.5% versus 3.5%, but the researchers point out that all eccentric lesions belonged to the asymmetric lesions group.
Writing in JACC Cardiovascular Interventions, Serruys et al conclude that "the current study suggested that a single variable of the expansion index is not enough to predict future events without taking into consideration the homogeneity of the stent/scaffold expansion and it seemed that AI was a more discriminant parameter compared to the [expansion index]."
While Hong and Kim conclude that the findings suggest that "symmetric BVS, not EES, expansion is necessary to reduce the frequency of device-related clinical events. Clinicians should endeavor to correct stent symmetricity."
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JACC Cardiovasc Interv 2016; Advance online publication