1

Impact of technique on early and late outcomes following coronary Bioresorbable scaffold implantation: Analysis from the ABSORB trials

The ABSORB bioresorbable vascular scaffold (BVS) is a novel first-generation technology, which compared with contemporary metallic drug-eluting stents (DES) has thicker struts, different expansion characteristics, and loss of structural integrity during the active bioresorption process. Previous intra-vascular ultrasound (IVUS) studies have shown that the strongest predictors of thrombosis and restenosis with metallic DES are a small minimum stent area (MSA), untreated significant edge dissections, and untreated residual disease, and there is no reason to think that these parameters would be less important with BVS. Acute malapposition, which may increase the likelihood of intraluminal scaffold dismantling, may be even more important to prevent with BVS than with metallic DES. These concerns have led to the “PSP” concept, which stands for P repare the lesion, S ize the scaffold correctly, and P ost dilate all stent with high pressure, non-compliant balloon to achieve maximum apposition. This technique has been recommended to lower the rate of stent thrombosis. To understand the impact of this technique on the rate of stent thrombosis that was seen in the ABSORB III trial, Gregg Stone, MD, from Columbia University Medical Center, presented the pooled multivariable analysis from the ongoing ABSROB IV trial. The investigators pooled data from 2973 Absorb BVS-treated patients from four prospective trials (ABSORB II, ABSORB China, ABSORB Japan and ABSORB III) and one registry study (ABSORB Extend) into a single database. Outcomes up to 3 years were assessed according to pre-specified definitions of optimal technique, and Cox proportional hazards regression was used to determine the independent predictors of target lesion failure (TLF) and scaffold thrombosis from 0 to 1 year, 1–3 years and 0–3 years. Across the Absorb series of studies (n = 2973), 59.2% of patients got pre-dilation and only 12.4% of patients got optimal post-dilatation with scaffold thrombosis increasing from 0.8% at 30 days to 2.7% at 3 years. On multivariable analysis, vessel sizing was important for reducing scaffold thrombosis in the first year (HR 0.36; 95% CI [0.18, 0.72]; p = 0.004). The opposite was true for optimal pre-dilatation (HR 2.25; 95% CI [0.98, 5.19]; p = 0.056), though that technique became protective after the first year (HR 0.23; 95% CI [0.07, 0.74]; p = 0.01). Over 3-year follow-up, the effect of PSP techniques trended to beneficial to prevent scaffold thrombosis but without reaching statistical significance. A limitation of the study that was raised is the variability in follow-up period of the ABSORB studies that were included in the analysis. Furthermore, the reasons for technique choices were not recorded, and as these decisions were not randomized, the impact of unmeasured confounders cannot be ruled out. The bottom line is that data are emerging that indicate that optimizing technique when implanting the first-generation Absorb BVS can improve mid-term outcomes. Dr. Stone pointed out that avoiding BRS implantation in very small vessels (QCA RVD <2.25 mm), and routinely performing high pressure post-dilatation with a non-compliant balloon may reduce the rates of TLF and scaffold thrombosis. New insights regarding the impact of optimal technique on the early and late outcomes of Absorb BVS will emerge with the final 3-year data from ABSORB III, China and Japan, and when the ABSORB IV results become available.

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Two-year clinical outcomes of the ABSORB BVS compared EES: A propensity matched analysis of the BVS expand registry

Clinical trials often exclude patients with complex coronary lesions (long or calcified lesions and bifurcation lesions), so the results often don’t represent real life practice. Thus, Robert Jan van Geuns, MD, from Erasmus Medical Center in Rotterdam noted the need for registries to address the gap between clinical trials and real life practice. Bioresorbable vascular scaffold (BVS) Expand is a registry that was started in 2012 that included long coronary lesions, bifurcations, calcified lesions, ACS patients (non-ST elevation myocardial infarction). The registry didn’t include patients with previous history of coronary artery bypass graft surgery (CABG) or history of metallic stent in target vessel.

Between September 2012 and January 2015, out of a total of 3373 patients who received percutaneous coronary intervention (PCI), 485 received BVS stents. From the BVS cohort, 249 patients agreed to be part of the expanded follow up beyond 12 months. The authors showed the results of 18 months of follow up data that were published in the Journal of the American College of Cardiology: Cardiovascular Interventions in 2016. At 18 months, average lesion length was 22 mm, which is larger than that seen in ABSORB II trial (11 mm lesion length). 21% and 42% of patients who received BVS had bifurcation and moderately to severe calcification, respectively. Furthermore, the rate of implantation when the reference vessel diameter (RVD) is <2.25 was 32%. Results at 18-month follow-up were encouraging as the rate of target lesion revascularization (TLR) was 3.8% and definite scaffold thrombosis was 1.3%.

The aim of the registry is to investigate the two-year outcome of the BVS-Expand registry in a propensity matched analysis to everolimus-eluting metallic stent (EES). The endpoint was defined as all-cause mortality, POCE (patient oriented composite endpoint): all death, all MI and all revascularization, TLR, stent thrombosis and scaffold thrombosis. From September 2012 to January 2015, 1518 EES patients were matched with BVS patients in a 2:1 fashion using patient and procedural characteristics. Based on this matching process, 448 EES patients were matched with 244 BVS patients. Baseline characteristics were not significantly different with more smokers in the BVS group and more prior PCI in the EES group.

At two years, the POCE were similar in both groups. However, the rates of myocardial infarction and TLR were higher in the BVS group compared with EES (6.1% vs. 2.1%, p = 0.007 and 6.1% vs. 2.9%, p = 0.05, respectively). However, the rate of definite device thrombosis was similar in the two groups (1.3% vs. 0.9%, p = 0.574). The Kaplan–Meier curves for 2-year POCE and definite device thrombosis were not significant (Log rank p = 0.408 and 0.574, respectively). The investigators concluded that in this real-world complex patient group with low incidence of post-dilatation, at 2-year follow up, despite higher rate of myocardial infarction and trends toward higher TLR rates in the BVS group, there was no difference in the rate of POCE or device thrombosis between BVS or EES.

2

Two-year clinical outcomes of the ABSORB BVS compared EES: A propensity matched analysis of the BVS expand registry

Clinical trials often exclude patients with complex coronary lesions (long or calcified lesions and bifurcation lesions), so the results often don’t represent real life practice. Thus, Robert Jan van Geuns, MD, from Erasmus Medical Center in Rotterdam noted the need for registries to address the gap between clinical trials and real life practice. Bioresorbable vascular scaffold (BVS) Expand is a registry that was started in 2012 that included long coronary lesions, bifurcations, calcified lesions, ACS patients (non-ST elevation myocardial infarction). The registry didn’t include patients with previous history of coronary artery bypass graft surgery (CABG) or history of metallic stent in target vessel.

Between September 2012 and January 2015, out of a total of 3373 patients who received percutaneous coronary intervention (PCI), 485 received BVS stents. From the BVS cohort, 249 patients agreed to be part of the expanded follow up beyond 12 months. The authors showed the results of 18 months of follow up data that were published in the Journal of the American College of Cardiology: Cardiovascular Interventions in 2016. At 18 months, average lesion length was 22 mm, which is larger than that seen in ABSORB II trial (11 mm lesion length). 21% and 42% of patients who received BVS had bifurcation and moderately to severe calcification, respectively. Furthermore, the rate of implantation when the reference vessel diameter (RVD) is <2.25 was 32%. Results at 18-month follow-up were encouraging as the rate of target lesion revascularization (TLR) was 3.8% and definite scaffold thrombosis was 1.3%.

The aim of the registry is to investigate the two-year outcome of the BVS-Expand registry in a propensity matched analysis to everolimus-eluting metallic stent (EES). The endpoint was defined as all-cause mortality, POCE (patient oriented composite endpoint): all death, all MI and all revascularization, TLR, stent thrombosis and scaffold thrombosis. From September 2012 to January 2015, 1518 EES patients were matched with BVS patients in a 2:1 fashion using patient and procedural characteristics. Based on this matching process, 448 EES patients were matched with 244 BVS patients. Baseline characteristics were not significantly different with more smokers in the BVS group and more prior PCI in the EES group.

At two years, the POCE were similar in both groups. However, the rates of myocardial infarction and TLR were higher in the BVS group compared with EES (6.1% vs. 2.1%, p = 0.007 and 6.1% vs. 2.9%, p = 0.05, respectively). However, the rate of definite device thrombosis was similar in the two groups (1.3% vs. 0.9%, p = 0.574). The Kaplan–Meier curves for 2-year POCE and definite device thrombosis were not significant (Log rank p = 0.408 and 0.574, respectively). The investigators concluded that in this real-world complex patient group with low incidence of post-dilatation, at 2-year follow up, despite higher rate of myocardial infarction and trends toward higher TLR rates in the BVS group, there was no difference in the rate of POCE or device thrombosis between BVS or EES.