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Bioabsorbable stents in routine practice. New epoch in interventional cardiology
CRVASA-428; No. of Pages 6 cor et vasa xxx (2016) e1–e6
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Original research article
Bioabsorbable stents in routine practice. New epoch in interventional cardiology Jan Škvařil *, Miroslav Černohous, Martin Hajšl, Pavel Sedloň, Miroslav Zavoral, Martin Malý Department of Cardiology of Internal Clinic, Central Military Hospital – The Military University Hospital Prague, First Faculty of Medicine, Charles University, Prague, Czech Republic
article info
abstract
Article history:
Introduction: According to contemporary experience, bioabsorbable vascular scaffolding
Received 22 May 2016
(BVS) implantation represents promising perspective in cardiology interventions. In the
Received in revised form
cathlab of Central Military Hospital in Prague, the program of BVS implantation started in
10 November 2016
June 2013.
Accepted 16 November 2016
Patient cohort and methods: From June 2013 to October 2015, 107 procedures of BVS implanta-
Available online xxx
tion in 98 patients were performed. Total of 110 lesions were treated. In 9 patients BVS was
Keywords:
one procedure, always using BVS. Non-randomized data of three cohorts of patients were
Bioabsorbable vascular scaffolding
evaluated: STEMI (45 patients), NSTEMI (34 patients), and elective BVS implantations (31
implanted in two stages. In 3 patients, the intervention of two vessels was performed during
Primary PCI
patients). The three groups did not differ in basic demographic features. In STEMI group,
Elective PCI
initial thrombotic occlusion and consequent thrombaspiration were more often. In this
Quantitative coronary analysis
(STEMI) group, the evaluation of the procedure is supplemented by CT performance after 12 months. Results: The procedure was always technically successful except 1 case (NSTEMI). Residual diameter stenosis >20% was registered in 1 patient in each group. Except 1 case in STEMI group, final TIMI III flow was achieved in all cases. One patient died in NSTEMI group in consequence of definite stent thrombosis. The final angiographic result (recoil, residual stenosis) was evaluated with the aid of quantitative coronary analysis (QCA). It did not prove any statistically significant difference among the groups. The value of immediate recoil did not exceed 10% in all groups. Target lesion revascularization (TLR) was performed in two patients in STEMI group. Up to now, performed CT scans demonstrated persisting good results. Conclusion: In accordance with contemporary literary data, our experience proves safety and efficacy of BVS implantation during coronary interventions in selected patients. © 2016 Published by Elsevier Sp. z o.o. on behalf of The Czech Society of Cardiology.
* Corresponding author at: Department of Cardiology of Internal Clinic, Central Military Hospital – The Military University Hospital Prague, First Faculty of Medicine, Charles University, U Vojenské nemocnice 1200, Praha 6, Střešovice, Czech Republic. Mobile: +420 606914546. E-mail address: [email protected] (J. Škvařil). http://dx.doi.org/10.1016/j.crvasa.2016.11.007 0010-8650/© 2016 Published by Elsevier Sp. z o.o. on behalf of The Czech Society of Cardiology.
Please cite this article in press as: J. Škvařil et al., Bioabsorbable stents in routine practice. New epoch in interventional cardiology, Cor et Vasa (2016), http://dx.doi.org/10.1016/j.crvasa.2016.11.007
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Introduction At present, implantation of bioabsorbable vascular scaffolding (BVS) is still more often. Their spreading use is sometimes called as the fourth revolution in interventional cardiology [1]. Andreas Grüntzig performed the first balloon angioplasty in 1977. This method was linked with the constrictive remodeling of the vessel. Together with elastic recoil, it leads to restenosis in more than 30% of all cases. Negative vessel remodeling, however, is only one of the contributors for in-stent restenosis. Intimal hyperplasia or neoatherosclerosis are even more important. Bare metal stent (BMS) introduction reduced the restenosis rate by one-third in the first half of the 1990s. In consequence of permanently present metal, however, positive vessel remodeling was disabled. Early and late in-stent thrombosis became another problem. Drug eluting stents (DES) contributed to substantial progress, especially thanks to the significant reduction of the restenosis rate. The development of the second generation of DES enabled the safety profile improvement, particularly by the reduction of early and late restenosis as well as stent thrombosis (ST). The first-inhuman drug-eluting fully bioresorbable vascular scaffold was implanted in 2006 in New Zealand [2]. Presently used BVS has the properties of modern DES of the second generation. At the same time, it is made of fully absorbable material. Thus, positive vessel remodeling in time is expected, together with maintenance respectively restoration of the vasomotion. It also makes cardio-surgical procedure possible in the future. In contrast to metallic stents, often associated with artifacts, BVS enables the performance of multislice CT (MSCT) very well during follow-up [3]. At present, there is sufficient evidence of effective and safe use of BVS in elective implantation as well as in interventions in terms of acute coronary syndrome (ACS): STEMI and NSTEMI [4–7]. In our site, BVS was first time used in June 2013. This article presents prospective data of non-randomized patients treated electively as well as in terms of ACS (STEMI and NSTEMI).
Patients and methods Patients' cohort From June 2013 to October 2015, 98 patients were treated by BVS implantation. In this cohort, nine patients were treated using BVS in two stages. We have thus performed 107 procedures. In three patients, the intervention of two vessels was performed during one procedure, always using BVS. Total of 110 lesions, treated with BVS implantation, were evaluated. The patients treated by direct coronary intervention (d-PCI) with the diagnoses of STEMI were enrolled in the prospective registry PRAGUE-19 at the same time [7]. The whole cohort (by treated lesions) includes 45 patients (i.e., lesions) with STEMI, 34 patients (i.e., lesions) with NSTEMI, and 31 patients (i.e., lesions), where BVS was implanted in terms of elective procedure. Patients were not enrolled (i.e., BVS was not implanted) with estimated life expectancy shorter than the time, during which the BVS is fully absorbed (2–3 years). With respect to dual antiplatelet treatment of 12 months, BVS was
not implanted in patients, where this recommended 12 months DAPT administration was not possible. Further, the size of the available instrumentarium was also decisive (the diameter of commercially available BVS is from 2.5 to 3.5 mm). Thus BVS was not implanted in patients with estimated target vessel diameter <2.3 mm and >3.7 mm. In other cases, the vessel morphology played decisive role in stent selection. BVS was not used in severely tortuous vessels, calcified lesions without the possibility of the sufficient predilatation and in cases of high probability of substantial degree of recoil, i.e., with demand of the high radial strength. BVS was neither used in bifurcations, where the side branch diameter was more than 2 mm.
BVS and procedure characteristics In ABSORB study [4], the first version of BVS was used. Today modified version 1.1 BVS Absorb (Abbott Vascular, Santa Clara, CA, USA) is available. It is balloon expandable stent. It is formed by polylactic acid polymer backbone covered by a thin amorphous poly-D,L-lactate matrix and coated with antiproliferative drug everolimus in 1:1 ratio. The strut thickness is 150 mm. The stent degradation consists in hydrolysis of lactic acid, which is metabolized in the Krebs cycle to CO2 and H2O. Version 1.1 has improved morphology and thus higher radial strength and better flexibility with longer resorption, which, according to available studies with optical coherence tomography (OCT), lasts as long as 36 months. DAPT was administered to all patients. Besides ASA, we prefer ticagrelor (Brilique). In STEMI and NSTEMI patients, in case of angiographically apparent intracoronary thrombosis, thrombaspiration was performed. Administration of GP IIb/IIIa inhibitors was reserved for cases, where the final TIMI III flow was not achieved. All lesions were predilated with the balloon of the same diameter, as of the intended BVS. Stent was implanted only when optically appropriate balloon inflation was achieved without any waist or deformation. In reported patient file, predilatation was not used in 1 STEMI and 1 NSTEMI patient. In both cases, the initial coronarography finding was intracoronary thrombosis. In first step, thrombaspiration was used and BVS was implanted in the second step. The balloon of the stent was dilated with a higher pressure, i.e., 12–14 atm. The inflation was slow, i.e., 2 atm per 1 s, as recommended. Postdilatation was performed by non-compliant balloon with the diameter 0.25 mm larger than the nominal stent diameter. Mostly high pressures up to burst-rated values were used. The stent implantation result was estimated by quantitative coronary analysis (QCA), with the use of GE software. Following projections (scenes) were used for QCA evaluation: scene before BVS implantation without intracoronary wire after intracoronary nitroglycerine administration, scene with dilated stent balloon, and finally the same projection after BVS implantation. Maximal vessel lumen diameters were measured proximally and distally to stenosis. As a reference segment for evaluation, the averaged diameter of the coronary artery segment assumed without atherosclerotic disease, was used. The procedure was considered successful, when TIMI III was achieved in target vessel and the residual stenosis was < 20% of the vessel diameter according to QCA.
Please cite this article in press as: J. Škvařil et al., Bioabsorbable stents in routine practice. New epoch in interventional cardiology, Cor et Vasa (2016), http://dx.doi.org/10.1016/j.crvasa.2016.11.007
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Table 1 – Basic characteristics of patient file. Characteristics (lesions) Age Men Diabetes mellitus Smoker Hypertension Hyperlipoproteinemia Prev MI Prev PCI Prev AKB n VD 1 VD 2 VD 3 VD
STEMI (n = 45)
NSTEMI (n = 34)
Elective (n = 31)
p
p12
p13
p23
58.3 (11.1) 35 (76.1%) 9 (19.6%) 30 (65.2%) 28 (60.9%) 36 (78.3%) 0 (0.0%) 0 (0.0%) 0 (0.0%)
53.5 (10.9) 19 (63.3%) 4 (13.3%) 15 (50.0%) 20 (66.7%) 25 (83.3%) 4 (13.3%) 4 (13.3%) 0 (0.0%)
60.7 (9.3) 29 (93.5%) 9 (29.0%) 12 (38.7%) 18 (58.1%) 25 (80.6%) 13 (41.9%) 15 (48.4%) 1 (3.2%)
0.026 0.014 0.315 0.067 0.769 0.951 <0.001 <0.001 0.570 0.026
0.152 0.660 0.908 0.552 0.952 0.988 0.063 0.063 1.000 0.956
0.689 0.177 0.798 0.102 0.994 1.000 <0.001 <0.001 1.000 0.041
0.025 0.015 0.509 0.828 0.936 1.000 0.062 0.015 1.000 0.077
30 (65.2%) 11 (23.9%) 5 (10.9%)
20 (66.7%) 5 (16.7%) 5 (16.7%)
10 (32.3%) 12 (38.7%) 9 (29.0%)
In STEMI patients enrolled to Prague 19 study, MSCT was performed after 12 months according to study protocol.
Statistical analysis For continuous variables, mean and standard deviation and absolute and relative frequencies (percentage) for categorical variables were used. Three groups were compared. The comparison is made by analysis of variance (continuous variables) and Fisher's exact test (categorical variables). Šidák's procedure of multiple comparison was used to identify the differing pairs of groups. The equability of data distribution in individual categories was verified by the goodness-of-test. Basically it was tested, whether the three groups (1 – STEMI, 2 – NSTEMI, and 3 – elective) can be considered equivalent (appropriate p-value is in p column). In case of statistically significant difference (p < 0.05), the comparison was made by couples (p12 for STEMI vs. NSTEMI, p13 for STEMI vs. elective, and p23 for NSTEMI vs. elective). For data analysis, the software IBM SPSS 21 for Windows was used.
Results During given period, 98 patients in the three groups were treated. 107 procedures with BVS implantation were performed with treatment of 110 lesions (i.e., 110 BVS were implanted). In nine patients, BVS was used in two stages. In three patients, two vessels were treated using BVS during one session. The three groups (i.e., STEMI, NSTEMI, elective) did not substantially differ in basic demographic parameters. Patients with elective BVS implantation were older. The men were more represented in all three groups. There are differences concerning clinical features. For STEMI patients, it is mostly the first manifestation of coronary artery disease (CAD). Conversely almost half of the elective patients already suffered myocardial infarction in the past. The same situations are with previous intervention. Another difference is found in number of involved vessels. Using goodness-of-fit test, we find out that while in elective patients 1VD, 2VD, and MVD are presented almost equally by thirds (p = 0.800), in STEMI and NSTEMI
patients, one vessel disease ‘‘infarct vessel’’ is more often ( p < 0.001). Basic characteristics of patient file are summarized in Table 1. Comparing the results of intervention between groups, no differences were found in number of implanted stents, their diameter, and length. There were not statistically significant differences in QCA evaluation between groups. In each group, there was always one patient with residual stenosis >20%. Except one patient in STEMI group with residual TIMI II flow and the need of GP IIb/IIIa inhibitors administration, in all other cases final TIMI III flow was achieved. In terms of ‘‘intention-to-treat,’’ one procedure (NSTEMI) was not technically successful. Despite repeated predilatation, it was not possible to put BVS through and so finally DES (Xience 3.5/ 24 mm) was implanted to angulated proximal segment of LAD. After BVS implantation, acute recoil was comparable in all groups and did not exceed 10%. In STEMI group, two patients (0.9%) died from noncardiac reasons within half a year after the procedure. In one case, it was caused by generalized malignity (not known and diagnosed in time of intervention). The second patient died of COPD exacerbation leading to respiratory failure, who was treated in regional hospital. In STEMI group, target lesion revascularization (TLR) occurred in two cases (0.9%). In one patient, simple drug eluting balloon (DEB) redilatation was performed. Second patient had severe LV dysfunction and probably successive treated-vessel-closure as it was found during recoronarography. Recanalization was not technically successful. Patient is further treated conservatively and ICD was implanted during follow-up. In NSTEMI group, definitive early stent thrombosis occurred in one case (0.34%) on sixth day after urgent intervention of distal left main. Thrombosis was proved during recoronarography. Repeated intervention was not successful and patient died. Another patient from this (NSTEMI) group suffered periprocedural transient ischemic attack (TIA) with quick complete recovery. In one case, intended procedure (subostial LAD stenosis) was extended to intervention of bifurcation LAD-RCx with left main (LM) stenting. DES was implanted to LM and RCx ostium, while LAD ostium was covered with BVS. The angiographic result was optimal and exercise stress test (SPECT), performed 6 months later, was negative. In two patients, successful treatment of two different
Please cite this article in press as: J. Škvařil et al., Bioabsorbable stents in routine practice. New epoch in interventional cardiology, Cor et Vasa (2016), http://dx.doi.org/10.1016/j.crvasa.2016.11.007
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Table 2 – Procedural data and results. Characteristics (lesions) Number of stents Treated vessel LAD RCx RCA Other Thrombaspiration Predilatation Postdilatation BVS diameter BVS length 100% stenosis before Stenosis before Stenosis after Stenosis after >20% Mean scaffold diameter during deployment Mean vessel diameter post BVS implantation Acute recoil TIMI before 0 1 2 3 TIMI after 0 1 2 3
STEMI (n = 45)
NSTEMI (n = 34)
Elective (n = 31)
1.2 (0.38)
1.21 (0.61)
1.42 (0.72)
18 (40%) 9 (20%) 18 (40%) 0 (0.0%) 17 (37.8%) 44 (97.7%) 41 (91.1%) 3.27 (0.29) 26.7 (10.9) 30 (66.6%) 95.76 (7.72) 6.42 (4.17) 1 (2.2%) 3.12 (0.28) 2.86 (0.27) 8.36 (2.21)
14 (41.2%) 13 (38.2%) 6 (17.6%) 1 (2.9%) 1 (2.9%) 32 (94.1%) 24 (70.6%) 3.24 (0.33) 26.8 (16.6) 3 (8.8%) 87.68 (10.06) 3.87 (5.95) 1 (2.9%) 3.08 (0.31) 2.84 (0.29) 7.81 (2.31)
14 (45.2%) 9 (29.0%) 7 (22.6%) 1 (3.2%) 0 (0.0%) 31 (100.0%) 25 (80.6%) 3.18 (0.35) 32.3 (16.0) 2 (6.5%) 81.92 (11.37) 6.56 (5.13) 1 (3.2%) 3.04 (0.34) 2.76 (0.32) 9.17 (3.18)
29 (63.0%) 4 (8.7%) 11 (23.9%) 1 (2.2%)
3 (9.1%) 0 (0.0%) 10 (29.4%) 21 (63.6%)
2 (6.5%) 0 (0.0%) 1 (3.2%) 28 (90.3%)
0 (0.0%) 0 (0.0%) 1 (2.2%) 44 (97.7%)
0 (0.0%) 0 (0.0%) 0 (0.0%) 34 (100.0%)
0 (0.0%) 0 (0.0%) 0 (0.0%) 31 (100.0%)
vessels was performed in one session because of inability to determine the culprit lesion under NSTEMI conditions. In the group of elective BVS implantations, neither serious complications nor TLR was registered, except one technically unsuccessful procedure mentioned above. In four cases, combination of BVS and DES was used to treat one lesion. In one patient, two vessels were treated with BVS in one session and full revascularization was completed in second step, again with BVS implantation. Procedural characteristics and results are summarized in Table 2.
Discussion The results of our prospective follow up well correspond with contemporary literary data. The use of newer generation of BVS is simple and safe and the results are comparable with data of DES. Despite larger crossing profile and presumption of more complicated placement, only one procedure was not technically successful. In ABSORB II study in Absorb group, the rate of definite stent thrombosis was 0.6% [8]. In our cohort, it occurred in one case (1.1%). The experiences demonstrate the need of proper BVS implantation. Predilatation with balloon of the same diameter as BVS is necessary. In our patients' cohort predilatation was used in all cases except two with initial thrombaspiration. The best possible stent strut apposition is emphasized. BVS has less radial strength compared to DES or BMS. In reference to estimated larger acute recoil, it is recommended larger scaffold-to-artery diameter ratio [9]. The value of immediate recoil did not exceed 10% in all
p12
p13
0.174 0.246
0.934 0.212
0.181 0.841
0.514 0.986
<0.001 1.000 0.157 0.454 0.197 <0.001 <0.001 0.049 1.000 0.475 0.276 0.103 <0.001
0.001 1.000 0.213 0.971 1.000 <0.001 0.001 0.083 1.000 0.914 0.982 0.726 <0.001
<0.001 1.000 0.705 0.511 0.267 <0.001 <0.001 0.999 1.000 0.534 0.313 0.427 <0.001
1.000 1.000 0.915 0.808 0.344 1.000 0.053 0.100 1.000 0.910 0.576 0.100 0.047
1.000
1.000
1.000
1.000
p
p23
groups of our cohort. As apparent (Table 2), mean scaffold diameter during deployment exceeds the mean vessel diameter immediately after BVS implantation. Thus scaffold-to-artery diameter ratio equals or rather goes beyond the value of 1.0. Besides scaffold-to-artery diameter ratio, the role of postdilatation is discussed [10]. We perform it routinely in majority of patients. Because of increased risk of acute and early stent thrombosis in more patients, where the balance is shifted in favor of procoagulation (patients with acute coronary syndrome), the optimal stent apposition is crucial [11,12]. In STEMI patients, we therefore carry out postdilatation in nearly 90% of cases. It is recommended to postdilate with higher pressure. In our workplace, non-compliant balloon is used with the diameter larger by 0.25 mm than appropriate BVS. To avoid edge dissection and to achieve the best possible apposition, we prefer multiple dilatation with shorter balloon. Interestingly, in our cohort, similarly in all three groups, mean BVS length is rather higher. We explain it both by the lesion characteristics (length), and by the effort to cover safely and carefully the whole lesion. At present BVS use is limited for ‘‘suitable’’ lesions. In contrast, heavily calcified, tortuous sections represent a problem. Sufficient predilatation is seldom possible and the presumption of recoil is higher. Contemporary BVS construction and the scale of available sizes is another limitation as demonstrated by IVUS and in particular OCT studies; the BVS diameter is often underestimated. This leads to poor apposition and higher risk of ST [13–15]. In addition, following recoil further decreases MLA. This was probably the reason of ST in our patient, where LM of ACS was intervened and where the
Please cite this article in press as: J. Škvařil et al., Bioabsorbable stents in routine practice. New epoch in interventional cardiology, Cor et Vasa (2016), http://dx.doi.org/10.1016/j.crvasa.2016.11.007
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diameter of available BVS might not be sufficient. At present (with contemporary equipment), the question of LM interventions is not reliably answered. The questions concerning the interventions of bifurcation stenoses with BVS are discussed as well. At present, it is not recommended to intervene bifurcations with side branch diameter >2 mm [16,17]. In our cohort, such intervention was performed in younger patient with 1 VD (LAD). After BVS implantation and postdilatation progressive distal dissection appeared, involving LAD-RD (3 mm) bifurcation. 3 BVSs were implanted with kissing postdilatation. Control recoronarography proved persisting optimal result after 9 months and the stress test (SPECT) was negative 1 year after intervention as well. Our data concerning the distribution of individual treated coronary vessels demonstrate interesting, however, wellknown fact. Although it is not statistically significant, in NSTEMI and elective group, individual vascular beds are represented proportionally, while in STEMI group LAD and RCA are more frequent at the expense of RCx. It may be the consequence of underestimation of posterior STEMI, when conventional 12-lead ECG is used. However, the analysis of TIMI flow before the intervention does not confirm this speculation. In this characteristics, there is a borderline statistical coincidence rather between NSTEMI and elective groups. On the basis of experiences with OCT, when more than 96% of struts were covered with endothelium after half a year, in ABSORB II study it was demanded to administer DAPT at least for 6 months [18]. In our department, we prefer DAPT administration optimally for 12 months. From available medicaments, we give priority to ticagrelor [19]. In patients where planning of 12 months DAPT administration is not possible (mostly atrial fibrillation with higher CHA2DS-VASc score, perspective of operation, etc.), we do not use BVS. On one hand, BVS is suitable for younger patients with less extensive coronary finding. Complete bioabsorption within 2– 3 years [20] enables positive vessel remodeling and possible recovery of physiological vascular motorics. This, together with strict secondary prevention, seems to be more perspective than rigid vascular segment without physiological reactions of the vessel with life-long ingrown metallic structure. In this respect, however, some late results are not clear and convincing. Recently published two large randomized trials did not show any clinical advantages compared with an everolimus-eluting metal stent in long-term follow up [21,22]. Three-year results of the ABSORB II trial did not meet the mechanistic co-primary end-point of superior vasomotor reactivity in Absorb group. On the other hand, due to aging of the population and better overall medical care, simple coronary lesions are ever less frequent at the expense of complex and demanding coronary involvement. In this respect, BVS may represent a promising perspective, since in character (bioabsorption) their use enables in case of further progress of coronary affection surgical revascularization in the future without substantial morphological limitations.
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PROSPECT ABSORB, etc.). Further development is expected in several areas. It is partly the size and construction of BVS. This could extend the use of diameters beyond contemporary limitations and thus to intervene the lesions, where contemporary reliable data are absent or incomplete (left main ACS, coronary bifurcations, bypass grafts, etc.). Technological innovations will obviously lead to better physical properties (lower crossing profile and greater radial strength), which again will enable the interventions of more complex and complicated lesions. Similarly to third generation of DES, where the necessary time period of DAPT administration is shortened to 1 month, analogous progress is to be expected also in case of BVS. At present, we approach the border of one million of implanted BVS all over the world. Estimation is that in 2017 BVS may represent as far as 50% of all implanted stents [23]. Recently, Food and Drug Administration's (FDAs) Circulatory Systems Device Panel convened to consider whether the FDA should approve Abbott Vascular's Absorb GT1 Bioresorbable Vascular Scaffold with successful and encouraging result of the following panel voting.
Limitation In presented work, prospective non-randomized data are compared. With regard to characteristic of individual three subgroups, the randomization between them was not possible. Neither is possible to set universal and definitive conclusions because of relatively small amount of patients in individual subgroups. As far as follow up is concerned, certainly it will be contribute to replace semiquantitative MSCT evaluation by quantitative CT analysis.
Conclusion In accordance with contemporary literary data, our experience proves safety and efficacy of the use of BVS in coronary interventions in selected groups of patients. On account of up to now promising results, we can expect the increase of BVS use in the near future at the expense of conventional metallic stents (DES). Improved technology of the new BVS type (Absorb GT1) and size expansion of available BVS are supposed to enable interventions of more complicated and complex lesions.
Conflict of interest None declared.
Ethical statement Authors state that the research was conducted according to ethical standards.
Perspective After breakthrough studies (ABSORB, ABSORB II), several other studies are in progress at present and others are planned (ABSORB III – recently published, ABSORB IV, AIDA, EVERBIO II,
Funding body None.
Please cite this article in press as: J. Škvařil et al., Bioabsorbable stents in routine practice. New epoch in interventional cardiology, Cor et Vasa (2016), http://dx.doi.org/10.1016/j.crvasa.2016.11.007
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Please cite this article in press as: J. Škvařil et al., Bioabsorbable stents in routine practice. New epoch in interventional cardiology, Cor et Vasa (2016), http://dx.doi.org/10.1016/j.crvasa.2016.11.007
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Original research article
Bioabsorbable stents in routine practice. New epoch in interventional cardiology Jan Škvařil *, Miroslav Černohous, Martin Hajšl, Pavel Sedloň, Miroslav Zavoral, Martin Malý Department of Cardiology of Internal Clinic, Central Military Hospital – The Military University Hospital Prague, First Faculty of Medicine, Charles University, Prague, Czech Republic
article info
abstract
Article history:
Introduction: According to contemporary experience, bioabsorbable vascular scaffolding
Received 22 May 2016
(BVS) implantation represents promising perspective in cardiology interventions. In the
Received in revised form
cathlab of Central Military Hospital in Prague, the program of BVS implantation started in
10 November 2016
June 2013.
Accepted 16 November 2016
Patient cohort and methods: From June 2013 to October 2015, 107 procedures of BVS implanta-
Available online xxx
tion in 98 patients were performed. Total of 110 lesions were treated. In 9 patients BVS was
Keywords:
one procedure, always using BVS. Non-randomized data of three cohorts of patients were
Bioabsorbable vascular scaffolding
evaluated: STEMI (45 patients), NSTEMI (34 patients), and elective BVS implantations (31
implanted in two stages. In 3 patients, the intervention of two vessels was performed during
Primary PCI
patients). The three groups did not differ in basic demographic features. In STEMI group,
Elective PCI
initial thrombotic occlusion and consequent thrombaspiration were more often. In this
Quantitative coronary analysis
(STEMI) group, the evaluation of the procedure is supplemented by CT performance after 12 months. Results: The procedure was always technically successful except 1 case (NSTEMI). Residual diameter stenosis >20% was registered in 1 patient in each group. Except 1 case in STEMI group, final TIMI III flow was achieved in all cases. One patient died in NSTEMI group in consequence of definite stent thrombosis. The final angiographic result (recoil, residual stenosis) was evaluated with the aid of quantitative coronary analysis (QCA). It did not prove any statistically significant difference among the groups. The value of immediate recoil did not exceed 10% in all groups. Target lesion revascularization (TLR) was performed in two patients in STEMI group. Up to now, performed CT scans demonstrated persisting good results. Conclusion: In accordance with contemporary literary data, our experience proves safety and efficacy of BVS implantation during coronary interventions in selected patients. © 2016 Published by Elsevier Sp. z o.o. on behalf of The Czech Society of Cardiology.
* Corresponding author at: Department of Cardiology of Internal Clinic, Central Military Hospital – The Military University Hospital Prague, First Faculty of Medicine, Charles University, U Vojenské nemocnice 1200, Praha 6, Střešovice, Czech Republic. Mobile: +420 606914546. E-mail address: [email protected] (J. Škvařil). http://dx.doi.org/10.1016/j.crvasa.2016.11.007 0010-8650/© 2016 Published by Elsevier Sp. z o.o. on behalf of The Czech Society of Cardiology.
Please cite this article in press as: J. Škvařil et al., Bioabsorbable stents in routine practice. New epoch in interventional cardiology, Cor et Vasa (2016), http://dx.doi.org/10.1016/j.crvasa.2016.11.007
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Introduction At present, implantation of bioabsorbable vascular scaffolding (BVS) is still more often. Their spreading use is sometimes called as the fourth revolution in interventional cardiology [1]. Andreas Grüntzig performed the first balloon angioplasty in 1977. This method was linked with the constrictive remodeling of the vessel. Together with elastic recoil, it leads to restenosis in more than 30% of all cases. Negative vessel remodeling, however, is only one of the contributors for in-stent restenosis. Intimal hyperplasia or neoatherosclerosis are even more important. Bare metal stent (BMS) introduction reduced the restenosis rate by one-third in the first half of the 1990s. In consequence of permanently present metal, however, positive vessel remodeling was disabled. Early and late in-stent thrombosis became another problem. Drug eluting stents (DES) contributed to substantial progress, especially thanks to the significant reduction of the restenosis rate. The development of the second generation of DES enabled the safety profile improvement, particularly by the reduction of early and late restenosis as well as stent thrombosis (ST). The first-inhuman drug-eluting fully bioresorbable vascular scaffold was implanted in 2006 in New Zealand [2]. Presently used BVS has the properties of modern DES of the second generation. At the same time, it is made of fully absorbable material. Thus, positive vessel remodeling in time is expected, together with maintenance respectively restoration of the vasomotion. It also makes cardio-surgical procedure possible in the future. In contrast to metallic stents, often associated with artifacts, BVS enables the performance of multislice CT (MSCT) very well during follow-up [3]. At present, there is sufficient evidence of effective and safe use of BVS in elective implantation as well as in interventions in terms of acute coronary syndrome (ACS): STEMI and NSTEMI [4–7]. In our site, BVS was first time used in June 2013. This article presents prospective data of non-randomized patients treated electively as well as in terms of ACS (STEMI and NSTEMI).
Patients and methods Patients' cohort From June 2013 to October 2015, 98 patients were treated by BVS implantation. In this cohort, nine patients were treated using BVS in two stages. We have thus performed 107 procedures. In three patients, the intervention of two vessels was performed during one procedure, always using BVS. Total of 110 lesions, treated with BVS implantation, were evaluated. The patients treated by direct coronary intervention (d-PCI) with the diagnoses of STEMI were enrolled in the prospective registry PRAGUE-19 at the same time [7]. The whole cohort (by treated lesions) includes 45 patients (i.e., lesions) with STEMI, 34 patients (i.e., lesions) with NSTEMI, and 31 patients (i.e., lesions), where BVS was implanted in terms of elective procedure. Patients were not enrolled (i.e., BVS was not implanted) with estimated life expectancy shorter than the time, during which the BVS is fully absorbed (2–3 years). With respect to dual antiplatelet treatment of 12 months, BVS was
not implanted in patients, where this recommended 12 months DAPT administration was not possible. Further, the size of the available instrumentarium was also decisive (the diameter of commercially available BVS is from 2.5 to 3.5 mm). Thus BVS was not implanted in patients with estimated target vessel diameter <2.3 mm and >3.7 mm. In other cases, the vessel morphology played decisive role in stent selection. BVS was not used in severely tortuous vessels, calcified lesions without the possibility of the sufficient predilatation and in cases of high probability of substantial degree of recoil, i.e., with demand of the high radial strength. BVS was neither used in bifurcations, where the side branch diameter was more than 2 mm.
BVS and procedure characteristics In ABSORB study [4], the first version of BVS was used. Today modified version 1.1 BVS Absorb (Abbott Vascular, Santa Clara, CA, USA) is available. It is balloon expandable stent. It is formed by polylactic acid polymer backbone covered by a thin amorphous poly-D,L-lactate matrix and coated with antiproliferative drug everolimus in 1:1 ratio. The strut thickness is 150 mm. The stent degradation consists in hydrolysis of lactic acid, which is metabolized in the Krebs cycle to CO2 and H2O. Version 1.1 has improved morphology and thus higher radial strength and better flexibility with longer resorption, which, according to available studies with optical coherence tomography (OCT), lasts as long as 36 months. DAPT was administered to all patients. Besides ASA, we prefer ticagrelor (Brilique). In STEMI and NSTEMI patients, in case of angiographically apparent intracoronary thrombosis, thrombaspiration was performed. Administration of GP IIb/IIIa inhibitors was reserved for cases, where the final TIMI III flow was not achieved. All lesions were predilated with the balloon of the same diameter, as of the intended BVS. Stent was implanted only when optically appropriate balloon inflation was achieved without any waist or deformation. In reported patient file, predilatation was not used in 1 STEMI and 1 NSTEMI patient. In both cases, the initial coronarography finding was intracoronary thrombosis. In first step, thrombaspiration was used and BVS was implanted in the second step. The balloon of the stent was dilated with a higher pressure, i.e., 12–14 atm. The inflation was slow, i.e., 2 atm per 1 s, as recommended. Postdilatation was performed by non-compliant balloon with the diameter 0.25 mm larger than the nominal stent diameter. Mostly high pressures up to burst-rated values were used. The stent implantation result was estimated by quantitative coronary analysis (QCA), with the use of GE software. Following projections (scenes) were used for QCA evaluation: scene before BVS implantation without intracoronary wire after intracoronary nitroglycerine administration, scene with dilated stent balloon, and finally the same projection after BVS implantation. Maximal vessel lumen diameters were measured proximally and distally to stenosis. As a reference segment for evaluation, the averaged diameter of the coronary artery segment assumed without atherosclerotic disease, was used. The procedure was considered successful, when TIMI III was achieved in target vessel and the residual stenosis was < 20% of the vessel diameter according to QCA.
Please cite this article in press as: J. Škvařil et al., Bioabsorbable stents in routine practice. New epoch in interventional cardiology, Cor et Vasa (2016), http://dx.doi.org/10.1016/j.crvasa.2016.11.007
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Table 1 – Basic characteristics of patient file. Characteristics (lesions) Age Men Diabetes mellitus Smoker Hypertension Hyperlipoproteinemia Prev MI Prev PCI Prev AKB n VD 1 VD 2 VD 3 VD
STEMI (n = 45)
NSTEMI (n = 34)
Elective (n = 31)
p
p12
p13
p23
58.3 (11.1) 35 (76.1%) 9 (19.6%) 30 (65.2%) 28 (60.9%) 36 (78.3%) 0 (0.0%) 0 (0.0%) 0 (0.0%)
53.5 (10.9) 19 (63.3%) 4 (13.3%) 15 (50.0%) 20 (66.7%) 25 (83.3%) 4 (13.3%) 4 (13.3%) 0 (0.0%)
60.7 (9.3) 29 (93.5%) 9 (29.0%) 12 (38.7%) 18 (58.1%) 25 (80.6%) 13 (41.9%) 15 (48.4%) 1 (3.2%)
0.026 0.014 0.315 0.067 0.769 0.951 <0.001 <0.001 0.570 0.026
0.152 0.660 0.908 0.552 0.952 0.988 0.063 0.063 1.000 0.956
0.689 0.177 0.798 0.102 0.994 1.000 <0.001 <0.001 1.000 0.041
0.025 0.015 0.509 0.828 0.936 1.000 0.062 0.015 1.000 0.077
30 (65.2%) 11 (23.9%) 5 (10.9%)
20 (66.7%) 5 (16.7%) 5 (16.7%)
10 (32.3%) 12 (38.7%) 9 (29.0%)
In STEMI patients enrolled to Prague 19 study, MSCT was performed after 12 months according to study protocol.
Statistical analysis For continuous variables, mean and standard deviation and absolute and relative frequencies (percentage) for categorical variables were used. Three groups were compared. The comparison is made by analysis of variance (continuous variables) and Fisher's exact test (categorical variables). Šidák's procedure of multiple comparison was used to identify the differing pairs of groups. The equability of data distribution in individual categories was verified by the goodness-of-test. Basically it was tested, whether the three groups (1 – STEMI, 2 – NSTEMI, and 3 – elective) can be considered equivalent (appropriate p-value is in p column). In case of statistically significant difference (p < 0.05), the comparison was made by couples (p12 for STEMI vs. NSTEMI, p13 for STEMI vs. elective, and p23 for NSTEMI vs. elective). For data analysis, the software IBM SPSS 21 for Windows was used.
Results During given period, 98 patients in the three groups were treated. 107 procedures with BVS implantation were performed with treatment of 110 lesions (i.e., 110 BVS were implanted). In nine patients, BVS was used in two stages. In three patients, two vessels were treated using BVS during one session. The three groups (i.e., STEMI, NSTEMI, elective) did not substantially differ in basic demographic parameters. Patients with elective BVS implantation were older. The men were more represented in all three groups. There are differences concerning clinical features. For STEMI patients, it is mostly the first manifestation of coronary artery disease (CAD). Conversely almost half of the elective patients already suffered myocardial infarction in the past. The same situations are with previous intervention. Another difference is found in number of involved vessels. Using goodness-of-fit test, we find out that while in elective patients 1VD, 2VD, and MVD are presented almost equally by thirds (p = 0.800), in STEMI and NSTEMI
patients, one vessel disease ‘‘infarct vessel’’ is more often ( p < 0.001). Basic characteristics of patient file are summarized in Table 1. Comparing the results of intervention between groups, no differences were found in number of implanted stents, their diameter, and length. There were not statistically significant differences in QCA evaluation between groups. In each group, there was always one patient with residual stenosis >20%. Except one patient in STEMI group with residual TIMI II flow and the need of GP IIb/IIIa inhibitors administration, in all other cases final TIMI III flow was achieved. In terms of ‘‘intention-to-treat,’’ one procedure (NSTEMI) was not technically successful. Despite repeated predilatation, it was not possible to put BVS through and so finally DES (Xience 3.5/ 24 mm) was implanted to angulated proximal segment of LAD. After BVS implantation, acute recoil was comparable in all groups and did not exceed 10%. In STEMI group, two patients (0.9%) died from noncardiac reasons within half a year after the procedure. In one case, it was caused by generalized malignity (not known and diagnosed in time of intervention). The second patient died of COPD exacerbation leading to respiratory failure, who was treated in regional hospital. In STEMI group, target lesion revascularization (TLR) occurred in two cases (0.9%). In one patient, simple drug eluting balloon (DEB) redilatation was performed. Second patient had severe LV dysfunction and probably successive treated-vessel-closure as it was found during recoronarography. Recanalization was not technically successful. Patient is further treated conservatively and ICD was implanted during follow-up. In NSTEMI group, definitive early stent thrombosis occurred in one case (0.34%) on sixth day after urgent intervention of distal left main. Thrombosis was proved during recoronarography. Repeated intervention was not successful and patient died. Another patient from this (NSTEMI) group suffered periprocedural transient ischemic attack (TIA) with quick complete recovery. In one case, intended procedure (subostial LAD stenosis) was extended to intervention of bifurcation LAD-RCx with left main (LM) stenting. DES was implanted to LM and RCx ostium, while LAD ostium was covered with BVS. The angiographic result was optimal and exercise stress test (SPECT), performed 6 months later, was negative. In two patients, successful treatment of two different
Please cite this article in press as: J. Škvařil et al., Bioabsorbable stents in routine practice. New epoch in interventional cardiology, Cor et Vasa (2016), http://dx.doi.org/10.1016/j.crvasa.2016.11.007
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Table 2 – Procedural data and results. Characteristics (lesions) Number of stents Treated vessel LAD RCx RCA Other Thrombaspiration Predilatation Postdilatation BVS diameter BVS length 100% stenosis before Stenosis before Stenosis after Stenosis after >20% Mean scaffold diameter during deployment Mean vessel diameter post BVS implantation Acute recoil TIMI before 0 1 2 3 TIMI after 0 1 2 3
STEMI (n = 45)
NSTEMI (n = 34)
Elective (n = 31)
1.2 (0.38)
1.21 (0.61)
1.42 (0.72)
18 (40%) 9 (20%) 18 (40%) 0 (0.0%) 17 (37.8%) 44 (97.7%) 41 (91.1%) 3.27 (0.29) 26.7 (10.9) 30 (66.6%) 95.76 (7.72) 6.42 (4.17) 1 (2.2%) 3.12 (0.28) 2.86 (0.27) 8.36 (2.21)
14 (41.2%) 13 (38.2%) 6 (17.6%) 1 (2.9%) 1 (2.9%) 32 (94.1%) 24 (70.6%) 3.24 (0.33) 26.8 (16.6) 3 (8.8%) 87.68 (10.06) 3.87 (5.95) 1 (2.9%) 3.08 (0.31) 2.84 (0.29) 7.81 (2.31)
14 (45.2%) 9 (29.0%) 7 (22.6%) 1 (3.2%) 0 (0.0%) 31 (100.0%) 25 (80.6%) 3.18 (0.35) 32.3 (16.0) 2 (6.5%) 81.92 (11.37) 6.56 (5.13) 1 (3.2%) 3.04 (0.34) 2.76 (0.32) 9.17 (3.18)
29 (63.0%) 4 (8.7%) 11 (23.9%) 1 (2.2%)
3 (9.1%) 0 (0.0%) 10 (29.4%) 21 (63.6%)
2 (6.5%) 0 (0.0%) 1 (3.2%) 28 (90.3%)
0 (0.0%) 0 (0.0%) 1 (2.2%) 44 (97.7%)
0 (0.0%) 0 (0.0%) 0 (0.0%) 34 (100.0%)
0 (0.0%) 0 (0.0%) 0 (0.0%) 31 (100.0%)
vessels was performed in one session because of inability to determine the culprit lesion under NSTEMI conditions. In the group of elective BVS implantations, neither serious complications nor TLR was registered, except one technically unsuccessful procedure mentioned above. In four cases, combination of BVS and DES was used to treat one lesion. In one patient, two vessels were treated with BVS in one session and full revascularization was completed in second step, again with BVS implantation. Procedural characteristics and results are summarized in Table 2.
Discussion The results of our prospective follow up well correspond with contemporary literary data. The use of newer generation of BVS is simple and safe and the results are comparable with data of DES. Despite larger crossing profile and presumption of more complicated placement, only one procedure was not technically successful. In ABSORB II study in Absorb group, the rate of definite stent thrombosis was 0.6% [8]. In our cohort, it occurred in one case (1.1%). The experiences demonstrate the need of proper BVS implantation. Predilatation with balloon of the same diameter as BVS is necessary. In our patients' cohort predilatation was used in all cases except two with initial thrombaspiration. The best possible stent strut apposition is emphasized. BVS has less radial strength compared to DES or BMS. In reference to estimated larger acute recoil, it is recommended larger scaffold-to-artery diameter ratio [9]. The value of immediate recoil did not exceed 10% in all
p12
p13
0.174 0.246
0.934 0.212
0.181 0.841
0.514 0.986
<0.001 1.000 0.157 0.454 0.197 <0.001 <0.001 0.049 1.000 0.475 0.276 0.103 <0.001
0.001 1.000 0.213 0.971 1.000 <0.001 0.001 0.083 1.000 0.914 0.982 0.726 <0.001
<0.001 1.000 0.705 0.511 0.267 <0.001 <0.001 0.999 1.000 0.534 0.313 0.427 <0.001
1.000 1.000 0.915 0.808 0.344 1.000 0.053 0.100 1.000 0.910 0.576 0.100 0.047
1.000
1.000
1.000
1.000
p
p23
groups of our cohort. As apparent (Table 2), mean scaffold diameter during deployment exceeds the mean vessel diameter immediately after BVS implantation. Thus scaffold-to-artery diameter ratio equals or rather goes beyond the value of 1.0. Besides scaffold-to-artery diameter ratio, the role of postdilatation is discussed [10]. We perform it routinely in majority of patients. Because of increased risk of acute and early stent thrombosis in more patients, where the balance is shifted in favor of procoagulation (patients with acute coronary syndrome), the optimal stent apposition is crucial [11,12]. In STEMI patients, we therefore carry out postdilatation in nearly 90% of cases. It is recommended to postdilate with higher pressure. In our workplace, non-compliant balloon is used with the diameter larger by 0.25 mm than appropriate BVS. To avoid edge dissection and to achieve the best possible apposition, we prefer multiple dilatation with shorter balloon. Interestingly, in our cohort, similarly in all three groups, mean BVS length is rather higher. We explain it both by the lesion characteristics (length), and by the effort to cover safely and carefully the whole lesion. At present BVS use is limited for ‘‘suitable’’ lesions. In contrast, heavily calcified, tortuous sections represent a problem. Sufficient predilatation is seldom possible and the presumption of recoil is higher. Contemporary BVS construction and the scale of available sizes is another limitation as demonstrated by IVUS and in particular OCT studies; the BVS diameter is often underestimated. This leads to poor apposition and higher risk of ST [13–15]. In addition, following recoil further decreases MLA. This was probably the reason of ST in our patient, where LM of ACS was intervened and where the
Please cite this article in press as: J. Škvařil et al., Bioabsorbable stents in routine practice. New epoch in interventional cardiology, Cor et Vasa (2016), http://dx.doi.org/10.1016/j.crvasa.2016.11.007
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diameter of available BVS might not be sufficient. At present (with contemporary equipment), the question of LM interventions is not reliably answered. The questions concerning the interventions of bifurcation stenoses with BVS are discussed as well. At present, it is not recommended to intervene bifurcations with side branch diameter >2 mm [16,17]. In our cohort, such intervention was performed in younger patient with 1 VD (LAD). After BVS implantation and postdilatation progressive distal dissection appeared, involving LAD-RD (3 mm) bifurcation. 3 BVSs were implanted with kissing postdilatation. Control recoronarography proved persisting optimal result after 9 months and the stress test (SPECT) was negative 1 year after intervention as well. Our data concerning the distribution of individual treated coronary vessels demonstrate interesting, however, wellknown fact. Although it is not statistically significant, in NSTEMI and elective group, individual vascular beds are represented proportionally, while in STEMI group LAD and RCA are more frequent at the expense of RCx. It may be the consequence of underestimation of posterior STEMI, when conventional 12-lead ECG is used. However, the analysis of TIMI flow before the intervention does not confirm this speculation. In this characteristics, there is a borderline statistical coincidence rather between NSTEMI and elective groups. On the basis of experiences with OCT, when more than 96% of struts were covered with endothelium after half a year, in ABSORB II study it was demanded to administer DAPT at least for 6 months [18]. In our department, we prefer DAPT administration optimally for 12 months. From available medicaments, we give priority to ticagrelor [19]. In patients where planning of 12 months DAPT administration is not possible (mostly atrial fibrillation with higher CHA2DS-VASc score, perspective of operation, etc.), we do not use BVS. On one hand, BVS is suitable for younger patients with less extensive coronary finding. Complete bioabsorption within 2– 3 years [20] enables positive vessel remodeling and possible recovery of physiological vascular motorics. This, together with strict secondary prevention, seems to be more perspective than rigid vascular segment without physiological reactions of the vessel with life-long ingrown metallic structure. In this respect, however, some late results are not clear and convincing. Recently published two large randomized trials did not show any clinical advantages compared with an everolimus-eluting metal stent in long-term follow up [21,22]. Three-year results of the ABSORB II trial did not meet the mechanistic co-primary end-point of superior vasomotor reactivity in Absorb group. On the other hand, due to aging of the population and better overall medical care, simple coronary lesions are ever less frequent at the expense of complex and demanding coronary involvement. In this respect, BVS may represent a promising perspective, since in character (bioabsorption) their use enables in case of further progress of coronary affection surgical revascularization in the future without substantial morphological limitations.
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PROSPECT ABSORB, etc.). Further development is expected in several areas. It is partly the size and construction of BVS. This could extend the use of diameters beyond contemporary limitations and thus to intervene the lesions, where contemporary reliable data are absent or incomplete (left main ACS, coronary bifurcations, bypass grafts, etc.). Technological innovations will obviously lead to better physical properties (lower crossing profile and greater radial strength), which again will enable the interventions of more complex and complicated lesions. Similarly to third generation of DES, where the necessary time period of DAPT administration is shortened to 1 month, analogous progress is to be expected also in case of BVS. At present, we approach the border of one million of implanted BVS all over the world. Estimation is that in 2017 BVS may represent as far as 50% of all implanted stents [23]. Recently, Food and Drug Administration's (FDAs) Circulatory Systems Device Panel convened to consider whether the FDA should approve Abbott Vascular's Absorb GT1 Bioresorbable Vascular Scaffold with successful and encouraging result of the following panel voting.
Limitation In presented work, prospective non-randomized data are compared. With regard to characteristic of individual three subgroups, the randomization between them was not possible. Neither is possible to set universal and definitive conclusions because of relatively small amount of patients in individual subgroups. As far as follow up is concerned, certainly it will be contribute to replace semiquantitative MSCT evaluation by quantitative CT analysis.
Conclusion In accordance with contemporary literary data, our experience proves safety and efficacy of the use of BVS in coronary interventions in selected groups of patients. On account of up to now promising results, we can expect the increase of BVS use in the near future at the expense of conventional metallic stents (DES). Improved technology of the new BVS type (Absorb GT1) and size expansion of available BVS are supposed to enable interventions of more complicated and complex lesions.
Conflict of interest None declared.
Ethical statement Authors state that the research was conducted according to ethical standards.
Perspective After breakthrough studies (ABSORB, ABSORB II), several other studies are in progress at present and others are planned (ABSORB III – recently published, ABSORB IV, AIDA, EVERBIO II,
Funding body None.
Please cite this article in press as: J. Škvařil et al., Bioabsorbable stents in routine practice. New epoch in interventional cardiology, Cor et Vasa (2016), http://dx.doi.org/10.1016/j.crvasa.2016.11.007
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Please cite this article in press as: J. Škvařil et al., Bioabsorbable stents in routine practice. New epoch in interventional cardiology, Cor et Vasa (2016), http://dx.doi.org/10.1016/j.crvasa.2016.11.007