Everolimus-Eluting Bioresorbable Vascular Scaffolds for STEMI
Everolimus-Eluting Bioresorbable Vascular Scaffolds for STEMI
As of 1 September 2012, the BVS (ABSORB; Abbott Vascular, Santa Clara, CA, USA) has been commercially available in the Netherlands. Based on previous experience and available evidence, reported in ABSORB Cohort A and B Trial our institution initiated the use of BVS for the treatment of patients presenting for PCI in everyday clinical practice, with a preference for patients with a good life expectancy as demonstrated by the presence of limited co-morbidities. As these patients might have more complex lesions compared with the ABSORB study patients the BVS-EXPAND registry was initiated. The BVS-EXPAND also included patients with ACS (unstable angina or non-STEMI). After the first experience with ACS patients and an interim analysis, a decision was made to extend BVS utilization to the treatment of STEMI.
As an additional measure for assessing the safety of a treatment approach with BVS in STEMI, optical coherence tomography (OCT) imaging was performed, according to clinical judgement, for a more comprehensive evaluation of the acute procedural outcome.
The present report is an investigator initiated, prospective, single-arm, single-centre study to assess feasibility and performance of the second-generation everolimus-eluting BVS for the treatment of patients presenting with STEMI.
Subjects enrolled were patients of ≥18-year-old admitted with STEMI, defined as at least 1 mm ST-segment elevation in two or more standard leads or at least 2 mm in two or more contiguous precordial leads or new left bundle branch block within 12 h after the onset of symptoms. Culprit lesions were located in vessels within the upper limit of 3.8 mm and the lower limit of 2.0 mm by online quantitative coronary angiography (QCA). The absorb BVS was implanted according to the manufacturer's indication on target-vessel diameter ranges and absorb BVS diameters to be used. The absorb BVS with a nominal diameter of 2.5 mm was implanted in vessels ≥2.0 and ≤3.0 mm by online QCA; the 3.0 mm BVS was implanted in vessels ≥2.5 and ≤3.3 mm by online QCA; the 3.5 mm BVS was implanted in vessels ≥3.0 and ≤3.8 mm. Given the manufacturer's indication on maximum scaffold expansion, for each nominal diameter a further expansion of 0.5 mm was allowed. Enrolled subjects were willing to comply with specified follow-up evaluation and to be contacted by telephone. Exclusion criteria comprise pregnancy, known intolerance to contrast medium, uncertain neurological outcome after cardiopulmonary resuscitation, previous percutaneous coronary intervention with the implantation of a metal stent, left main (LM) disease previous coronary artery bypass grafting (CABG), age superior to 75 years, and participation to another investigational drug or device study before reaching the primary endpoints. The enrolment period started on 1 November 2012 and ended on 30 March 2013. Dual antiplatelet therapy after the BVS implantation was planned to have a duration of 12 months. Baseline and post-BVS implantation QCA analysis, OCT analyses at post-BVS implantation, and clinical outcomes at the 30-day follow-up were evaluated.
Success rates were defined as follows: device success was the attainment of <30% final residual stenosis of the segment of the culprit lesion covered by the BVS, by angiographic visual estimation. Procedure success was defined as device success and no major peri-procedural complications (Emergent CABG, coronary perforation requiring pericardial drainage, residual dissection impairing vessel flow—TIMI-flow II or less). Clinical success was defined as procedural success and no in-hospital major adverse cardiac events (MACE). All deaths were considered cardiac unless an undisputed non-cardiac cause was identified. Myocardial infarction (MI) and scaffold thrombosis were defined according to the Academic Research Consortium definition. Target-lesion revascularization (TLR) was defined as clinically driven if at repeat angiography the diameter stenosis was >70%, or if a diameter stenosis >50% was present in association with (i) presence of recurrent angina pectoris, related to the target vessel; (ii) objective signs of ischaemia at rest (ECG changes) or during exercise test, related to the target vessel; and (iii) abnormal results of any functional diagnostic test.
The device-oriented endpoint target-lesion failure was defined as the composite of cardiac death, target-vessel MI, or ischaemia-driven TLR. Major adverse cardiac events defined as the composite of cardiac death, any re-infarction (Q- or non-Q-wave), emergent bypass surgery (CABG), or clinically driven TLR. Target-vessel failure (TVF) was defined as cardiac death, target-vessel MI, or clinically driven TVR.
This is an observational study, performed according to the privacy policy of the Erasmus MC and to the Erasmus MC regulations for the appropriate use of data in patient-oriented research, which are based on international regulations, including the declaration of Helsinki. The BVS received the CE mark for clinical use, indicated for improving coronary lumen diameter in patients with ischaemic heart disease due to de novo native coronary artery lesions with no restriction in terms of clinical presentation. Therefore, the BVS can be currently used routinely in Europe in different settings comprising the acute MI without a specific written informed consent in addition to the standard informed consent to the procedure. Given this background, a waiver from the hospital Ethical Committee was obtained for written informed consent, as according to Dutch law written consent is not required, if patients are not subject to acts other than as part of their regular treatment.
The second-generation everolimus-eluting BVS is a balloon expandable device consisting of a polymer backbone of poly-l-lactide acid (PLLA) coated with a thin layer of amorphous matrix of poly-d and -l-lactide acid (PDLLA) polymer (strut thickness 157 μm). The PDLLA controls the release of the antiproliferative drug everolimus (100 μg/cm), 80% of which is eluted within the first 30 days. Both PLLA and PDLLA are fully bioresorbable. The polymers are degraded via hydrolysis of the ester bonds and the resulting lactate and its oligomers are metabolized by the Krebs cycles. Small particles (<2 μm in diameter) may be also phagocytized and degraded by macrophages. According to preclinical studies, the time for complete bioresorption of the polymer backbone is ~2–3 years. The BVS edges contain two platinum markers for accurate visualization during angiography or other imaging modalities.
Quantitative coronary angiography (QCA) analyses were performed using the Coronary Angiography Analysis System (Pie Medical Imaging, Maastricht, Netherlands).
Analyses were performed at pre-procedure, after thombectomy, after balloon dilatation, and after the BVS implantation with a methodology already reported.
In case of thrombotic total occlusion, pre-procedure QCA analysis was performed as proximally as possible from the occlusion (in case of a side branch distally to the most proximal take off of the side branch). Intracoronary thrombus was angiographically identified and scored in five grades as previously described. Thrombus grade was assessed before procedure and after thombectomy.
The QCA measurements included reference vessel diameter (RVD)—calculated with interpolate method—percentage diameter stenosis, minimal lumen diameter (MLD), and maximal lumen diameter (Dmax). Acute gain was defined as post-procedural MLD minus pre-procedural MLD (MLD value equal to zero was applied when culprit vessel was occluded pre-procedurally). Complications occurring any time during the procedure, such as dissection, spasm, distal embolization, and no-reflow were reported. As additional information, MI SYNTAX I and MI SYNTAX II scores providing long-term risk stratification for mortality and MACE in patients presenting with STEMI were assessed.
Optical coherence tomography imaging after the BVS implantation was encouraged in all patients but was not mandatory, subordinated to device availability and left at the operator's discretion.
Therefore, OCT imaging of the culprit lesion after treatment was performed in a subset of the population. The image acquisition was performed with C7XR imaging console and the Dragonfly intravascular imaging catheter (both St. Jude Medical, St. Paul, MN, USA). Image acquisition has been previously described. Briefly, after positioning the OCT catheter distally to the most distal scaffold marker, the catheter is pulled back automatically at 20 mm/s with simultaneous contrast infusion by a power injector (flush rate 3–4 mL/s). In cases where the entire scaffold region was not imaged in one pullback, a second more proximal pullback was performed for complete visualization. Images were stored and analysed offline.
Analysis of the OCT images was performed with the St Jude/Lightlab offline analysis software (St. Jude Medical), using previously described methodology for BVS analysis. Analysis was performed in 1-mm longitudinal intervals within the treated culprit segment, after exclusion of frames with <75% lumen contour visibility. Lumen, scaffold, and incomplete scaffold apposition (ISA) area were calculated in accordance with standard methodology for analysis of bioresorbable scaffolds (Figure 1A and B), while in sites with overlapping scaffolds, analysis was performed using previously suggested modifications (Figure 1D). Specifically, the lumen contour is traced at the lumen border and in the abluminal (outer) side of apposed struts, while in the case of malapposed struts the contour is traced behind the malapposed struts. In cases where the scaffold struts are completely covered by tissue or thrombus, the lumen contour is traced above the prolapsing tissue (Figure 1C). The scaffold area is traced following interpolation of points located in the mid-point of the abluminal border of the black core in apposed struts and the mid-point of the abluminal strut frame border in malapposed or side branch-related struts, so that the scaffold area is identical to the lumen area in the absence of ISA and tissue prolapse. Incomplete scaffold apposition area is traced in the case of malapposed struts as the area delineated between the lumen and scaffold contours (Figure 1B).
(Enlarge Image)
Figure 1.
Methodology of optical coherence tomography analysis. (A) Good scaffold apposition and absence of incomplete scaffold apposition or tissue prolapse, (B) incomplete scaffold apposition, (C) sites with high tissue prolapse and struts completely covered by thrombus, and (D) overlapping scaffolds. Upper panel shows baseline images, middle panel shows quantitative measurements, and lower panel shows methodology for analysis. ISA, incomplete scaffold apposition; ATA, atherothrombotic area.
A special consideration should be mentioned concerning BVS analysis in MI with the presence of increased tissue prolapse and residual thrombus post-implantation (Figures 1C and 2). Tissue prolapse area can be quantified as the difference between the scaffold and the lumen area. For the calculation of prolapse area, in the case that one or more scaffold struts are completely covered by thrombus or tissue, the total black core area of these struts is also measured. Prolapse area is then calculated as [scaffold area + ISA area – lumen area – embedded black core area]. The area of non-attached intraluminal defects (e.g. thrombus) is also measured. Atherothrombotic area is then calculated as the sum of prolapse area and intraluminal defect area and normalized as a percent ratio of the scaffold area (atherothrombotic burden, ATB). It should be noted that in the case of bioresorbable scaffolds where measurements of the scaffold area are performed using the abluminal side of the scaffold struts, ATB is overestimated compared with metal platform stents where measurements of the stent area are performed from the adluminal (inner) side of the struts. Additionally, flow area was assessed as [scaffold area + ISA area – atherothrombotic area – total strut area] and the minimal flow area was recorded.
(Enlarge Image)
Figure 2.
Bioresorbable vascular scaffolds implantation in a culprit and a non-culprit lesion in myocardial infarction. (A) Coronary angiography demonstrating a stenotic lesion in proximal LAD (proximal non-culprit lesion) and a total occlusion of the mid-LAD (culprit lesion). (B) Angiography following thrombus aspiration. (C) Angiography following implantation of a 3.5 × 12 mm bioresorbable vascular scaffolds at the proximal LAD lesion and a 3.0 × 28 mm bioresorbable vascular scaffolds at the mid-LAD lesion. (D) Optical coherence tomography image from the proximal non-culprit lesion showing absence of tissue prolapse and thrombus in the 3.5 × 12 mm scaffold. (E and F) Optical coherence tomography images from the culprit lesion showing complete coverage of the bioresorbable vascular scaffolds by tissue prolapse and presence of small amount of intraluminal defect. (G) Three-dimensional optical coherence tomography rendering in the proximal non-culprit lesion with complete scaffold visualization indicating the absence of prolapsing material. (H) Conversely, in the three-dimensional rendering of the culprit lesion, the morphology of the bioresorbable vascular scaffolds cannot be fully visualized due to high levels of tissue prolapse (*).
A scaffold strut is defined as incompletely apposed when there is no contact between the abluminal border of the strut and the vessel wall. This does not include struts located in front of side branches or their ostium (polygon of confluence region), which are defined as side branch-related struts. Intraluminal struts that are part of adjacent clusters of apposed struts in overlapping scaffolds are also not considered malapposed. For illustrative proposes, OCT bi-dimensional images are reported by three-dimensional rendering by dedicated software (Intage Realia, KGT, Kyoto, Japan) (Figures 2 and 3).
(Enlarge Image)
Figure 3.
Bioresorbable vascular scaffold implantation in a thrombotic bifurcation lesion treated with provisional approach. (A) Coronary angiography pre-intervention. (B) Angiography following bioresorbable vascular scaffold implantation in the LAD, showing pinching of the ostium of the diagonal (D). (C) Final angiographic result following side branch dilation with 2.0 × 15 mm balloon. (D–F and J) Optical coherence tomography cross-sectional images and l-mode after bioresorbable vascular scaffolds implantation showing the compromise of the side branch after implantation and presence of thrombus at the side branch ostium. (G–I and K) Optical coherence tomography cross-sectional images and l-mode after side branch dilation, showing the opening of the carina of the side branch. (L and M) Three-dimensional reconstructions confirm the opening of the side branch ostium.
Continuous variables are presented as mean and standard deviation, and categorical variables are reported as count and percentages. Descriptive statistics was provided for all variables. The present study is intended to be a 'first experience investigation' evaluating feasibility and acute performance of the everolimus-eluting BVS for the treatment of patients presenting with STEMI. A patient population of at least 30 patients was planned to be included in the present study. Comparisons among multiple means were performed with analysis of variance (one-way ANOVA). Score (Wilson) confidence intervals were reported for measures of success. Type A intraclass correlation coefficients (ICCs) for absolute agreement were used for assessing intra- and interobserver agreement, while measurement error and 95% limits of agreement were assessed by Bland–Altman analysis. The ICCs were computed with a two-way random effects model (single measures). All statistical tests were performed with SPSS, version 15.0 for windows (IL, USA).
Methods
Rationale
As of 1 September 2012, the BVS (ABSORB; Abbott Vascular, Santa Clara, CA, USA) has been commercially available in the Netherlands. Based on previous experience and available evidence, reported in ABSORB Cohort A and B Trial our institution initiated the use of BVS for the treatment of patients presenting for PCI in everyday clinical practice, with a preference for patients with a good life expectancy as demonstrated by the presence of limited co-morbidities. As these patients might have more complex lesions compared with the ABSORB study patients the BVS-EXPAND registry was initiated. The BVS-EXPAND also included patients with ACS (unstable angina or non-STEMI). After the first experience with ACS patients and an interim analysis, a decision was made to extend BVS utilization to the treatment of STEMI.
As an additional measure for assessing the safety of a treatment approach with BVS in STEMI, optical coherence tomography (OCT) imaging was performed, according to clinical judgement, for a more comprehensive evaluation of the acute procedural outcome.
Study Design
The present report is an investigator initiated, prospective, single-arm, single-centre study to assess feasibility and performance of the second-generation everolimus-eluting BVS for the treatment of patients presenting with STEMI.
Subjects enrolled were patients of ≥18-year-old admitted with STEMI, defined as at least 1 mm ST-segment elevation in two or more standard leads or at least 2 mm in two or more contiguous precordial leads or new left bundle branch block within 12 h after the onset of symptoms. Culprit lesions were located in vessels within the upper limit of 3.8 mm and the lower limit of 2.0 mm by online quantitative coronary angiography (QCA). The absorb BVS was implanted according to the manufacturer's indication on target-vessel diameter ranges and absorb BVS diameters to be used. The absorb BVS with a nominal diameter of 2.5 mm was implanted in vessels ≥2.0 and ≤3.0 mm by online QCA; the 3.0 mm BVS was implanted in vessels ≥2.5 and ≤3.3 mm by online QCA; the 3.5 mm BVS was implanted in vessels ≥3.0 and ≤3.8 mm. Given the manufacturer's indication on maximum scaffold expansion, for each nominal diameter a further expansion of 0.5 mm was allowed. Enrolled subjects were willing to comply with specified follow-up evaluation and to be contacted by telephone. Exclusion criteria comprise pregnancy, known intolerance to contrast medium, uncertain neurological outcome after cardiopulmonary resuscitation, previous percutaneous coronary intervention with the implantation of a metal stent, left main (LM) disease previous coronary artery bypass grafting (CABG), age superior to 75 years, and participation to another investigational drug or device study before reaching the primary endpoints. The enrolment period started on 1 November 2012 and ended on 30 March 2013. Dual antiplatelet therapy after the BVS implantation was planned to have a duration of 12 months. Baseline and post-BVS implantation QCA analysis, OCT analyses at post-BVS implantation, and clinical outcomes at the 30-day follow-up were evaluated.
Definitions
Success rates were defined as follows: device success was the attainment of <30% final residual stenosis of the segment of the culprit lesion covered by the BVS, by angiographic visual estimation. Procedure success was defined as device success and no major peri-procedural complications (Emergent CABG, coronary perforation requiring pericardial drainage, residual dissection impairing vessel flow—TIMI-flow II or less). Clinical success was defined as procedural success and no in-hospital major adverse cardiac events (MACE). All deaths were considered cardiac unless an undisputed non-cardiac cause was identified. Myocardial infarction (MI) and scaffold thrombosis were defined according to the Academic Research Consortium definition. Target-lesion revascularization (TLR) was defined as clinically driven if at repeat angiography the diameter stenosis was >70%, or if a diameter stenosis >50% was present in association with (i) presence of recurrent angina pectoris, related to the target vessel; (ii) objective signs of ischaemia at rest (ECG changes) or during exercise test, related to the target vessel; and (iii) abnormal results of any functional diagnostic test.
The device-oriented endpoint target-lesion failure was defined as the composite of cardiac death, target-vessel MI, or ischaemia-driven TLR. Major adverse cardiac events defined as the composite of cardiac death, any re-infarction (Q- or non-Q-wave), emergent bypass surgery (CABG), or clinically driven TLR. Target-vessel failure (TVF) was defined as cardiac death, target-vessel MI, or clinically driven TVR.
Ethics
This is an observational study, performed according to the privacy policy of the Erasmus MC and to the Erasmus MC regulations for the appropriate use of data in patient-oriented research, which are based on international regulations, including the declaration of Helsinki. The BVS received the CE mark for clinical use, indicated for improving coronary lumen diameter in patients with ischaemic heart disease due to de novo native coronary artery lesions with no restriction in terms of clinical presentation. Therefore, the BVS can be currently used routinely in Europe in different settings comprising the acute MI without a specific written informed consent in addition to the standard informed consent to the procedure. Given this background, a waiver from the hospital Ethical Committee was obtained for written informed consent, as according to Dutch law written consent is not required, if patients are not subject to acts other than as part of their regular treatment.
Study Device
The second-generation everolimus-eluting BVS is a balloon expandable device consisting of a polymer backbone of poly-l-lactide acid (PLLA) coated with a thin layer of amorphous matrix of poly-d and -l-lactide acid (PDLLA) polymer (strut thickness 157 μm). The PDLLA controls the release of the antiproliferative drug everolimus (100 μg/cm), 80% of which is eluted within the first 30 days. Both PLLA and PDLLA are fully bioresorbable. The polymers are degraded via hydrolysis of the ester bonds and the resulting lactate and its oligomers are metabolized by the Krebs cycles. Small particles (<2 μm in diameter) may be also phagocytized and degraded by macrophages. According to preclinical studies, the time for complete bioresorption of the polymer backbone is ~2–3 years. The BVS edges contain two platinum markers for accurate visualization during angiography or other imaging modalities.
Quantitative Coronary Angiography Analysis
Quantitative coronary angiography (QCA) analyses were performed using the Coronary Angiography Analysis System (Pie Medical Imaging, Maastricht, Netherlands).
Analyses were performed at pre-procedure, after thombectomy, after balloon dilatation, and after the BVS implantation with a methodology already reported.
In case of thrombotic total occlusion, pre-procedure QCA analysis was performed as proximally as possible from the occlusion (in case of a side branch distally to the most proximal take off of the side branch). Intracoronary thrombus was angiographically identified and scored in five grades as previously described. Thrombus grade was assessed before procedure and after thombectomy.
The QCA measurements included reference vessel diameter (RVD)—calculated with interpolate method—percentage diameter stenosis, minimal lumen diameter (MLD), and maximal lumen diameter (Dmax). Acute gain was defined as post-procedural MLD minus pre-procedural MLD (MLD value equal to zero was applied when culprit vessel was occluded pre-procedurally). Complications occurring any time during the procedure, such as dissection, spasm, distal embolization, and no-reflow were reported. As additional information, MI SYNTAX I and MI SYNTAX II scores providing long-term risk stratification for mortality and MACE in patients presenting with STEMI were assessed.
Optical Coherence Tomography Image Acquisition and Analysis
Optical coherence tomography imaging after the BVS implantation was encouraged in all patients but was not mandatory, subordinated to device availability and left at the operator's discretion.
Therefore, OCT imaging of the culprit lesion after treatment was performed in a subset of the population. The image acquisition was performed with C7XR imaging console and the Dragonfly intravascular imaging catheter (both St. Jude Medical, St. Paul, MN, USA). Image acquisition has been previously described. Briefly, after positioning the OCT catheter distally to the most distal scaffold marker, the catheter is pulled back automatically at 20 mm/s with simultaneous contrast infusion by a power injector (flush rate 3–4 mL/s). In cases where the entire scaffold region was not imaged in one pullback, a second more proximal pullback was performed for complete visualization. Images were stored and analysed offline.
Analysis of the OCT images was performed with the St Jude/Lightlab offline analysis software (St. Jude Medical), using previously described methodology for BVS analysis. Analysis was performed in 1-mm longitudinal intervals within the treated culprit segment, after exclusion of frames with <75% lumen contour visibility. Lumen, scaffold, and incomplete scaffold apposition (ISA) area were calculated in accordance with standard methodology for analysis of bioresorbable scaffolds (Figure 1A and B), while in sites with overlapping scaffolds, analysis was performed using previously suggested modifications (Figure 1D). Specifically, the lumen contour is traced at the lumen border and in the abluminal (outer) side of apposed struts, while in the case of malapposed struts the contour is traced behind the malapposed struts. In cases where the scaffold struts are completely covered by tissue or thrombus, the lumen contour is traced above the prolapsing tissue (Figure 1C). The scaffold area is traced following interpolation of points located in the mid-point of the abluminal border of the black core in apposed struts and the mid-point of the abluminal strut frame border in malapposed or side branch-related struts, so that the scaffold area is identical to the lumen area in the absence of ISA and tissue prolapse. Incomplete scaffold apposition area is traced in the case of malapposed struts as the area delineated between the lumen and scaffold contours (Figure 1B).
(Enlarge Image)
Figure 1.
Methodology of optical coherence tomography analysis. (A) Good scaffold apposition and absence of incomplete scaffold apposition or tissue prolapse, (B) incomplete scaffold apposition, (C) sites with high tissue prolapse and struts completely covered by thrombus, and (D) overlapping scaffolds. Upper panel shows baseline images, middle panel shows quantitative measurements, and lower panel shows methodology for analysis. ISA, incomplete scaffold apposition; ATA, atherothrombotic area.
A special consideration should be mentioned concerning BVS analysis in MI with the presence of increased tissue prolapse and residual thrombus post-implantation (Figures 1C and 2). Tissue prolapse area can be quantified as the difference between the scaffold and the lumen area. For the calculation of prolapse area, in the case that one or more scaffold struts are completely covered by thrombus or tissue, the total black core area of these struts is also measured. Prolapse area is then calculated as [scaffold area + ISA area – lumen area – embedded black core area]. The area of non-attached intraluminal defects (e.g. thrombus) is also measured. Atherothrombotic area is then calculated as the sum of prolapse area and intraluminal defect area and normalized as a percent ratio of the scaffold area (atherothrombotic burden, ATB). It should be noted that in the case of bioresorbable scaffolds where measurements of the scaffold area are performed using the abluminal side of the scaffold struts, ATB is overestimated compared with metal platform stents where measurements of the stent area are performed from the adluminal (inner) side of the struts. Additionally, flow area was assessed as [scaffold area + ISA area – atherothrombotic area – total strut area] and the minimal flow area was recorded.
(Enlarge Image)
Figure 2.
Bioresorbable vascular scaffolds implantation in a culprit and a non-culprit lesion in myocardial infarction. (A) Coronary angiography demonstrating a stenotic lesion in proximal LAD (proximal non-culprit lesion) and a total occlusion of the mid-LAD (culprit lesion). (B) Angiography following thrombus aspiration. (C) Angiography following implantation of a 3.5 × 12 mm bioresorbable vascular scaffolds at the proximal LAD lesion and a 3.0 × 28 mm bioresorbable vascular scaffolds at the mid-LAD lesion. (D) Optical coherence tomography image from the proximal non-culprit lesion showing absence of tissue prolapse and thrombus in the 3.5 × 12 mm scaffold. (E and F) Optical coherence tomography images from the culprit lesion showing complete coverage of the bioresorbable vascular scaffolds by tissue prolapse and presence of small amount of intraluminal defect. (G) Three-dimensional optical coherence tomography rendering in the proximal non-culprit lesion with complete scaffold visualization indicating the absence of prolapsing material. (H) Conversely, in the three-dimensional rendering of the culprit lesion, the morphology of the bioresorbable vascular scaffolds cannot be fully visualized due to high levels of tissue prolapse (*).
A scaffold strut is defined as incompletely apposed when there is no contact between the abluminal border of the strut and the vessel wall. This does not include struts located in front of side branches or their ostium (polygon of confluence region), which are defined as side branch-related struts. Intraluminal struts that are part of adjacent clusters of apposed struts in overlapping scaffolds are also not considered malapposed. For illustrative proposes, OCT bi-dimensional images are reported by three-dimensional rendering by dedicated software (Intage Realia, KGT, Kyoto, Japan) (Figures 2 and 3).
(Enlarge Image)
Figure 3.
Bioresorbable vascular scaffold implantation in a thrombotic bifurcation lesion treated with provisional approach. (A) Coronary angiography pre-intervention. (B) Angiography following bioresorbable vascular scaffold implantation in the LAD, showing pinching of the ostium of the diagonal (D). (C) Final angiographic result following side branch dilation with 2.0 × 15 mm balloon. (D–F and J) Optical coherence tomography cross-sectional images and l-mode after bioresorbable vascular scaffolds implantation showing the compromise of the side branch after implantation and presence of thrombus at the side branch ostium. (G–I and K) Optical coherence tomography cross-sectional images and l-mode after side branch dilation, showing the opening of the carina of the side branch. (L and M) Three-dimensional reconstructions confirm the opening of the side branch ostium.
Statistical Analysis
Continuous variables are presented as mean and standard deviation, and categorical variables are reported as count and percentages. Descriptive statistics was provided for all variables. The present study is intended to be a 'first experience investigation' evaluating feasibility and acute performance of the everolimus-eluting BVS for the treatment of patients presenting with STEMI. A patient population of at least 30 patients was planned to be included in the present study. Comparisons among multiple means were performed with analysis of variance (one-way ANOVA). Score (Wilson) confidence intervals were reported for measures of success. Type A intraclass correlation coefficients (ICCs) for absolute agreement were used for assessing intra- and interobserver agreement, while measurement error and 95% limits of agreement were assessed by Bland–Altman analysis. The ICCs were computed with a two-way random effects model (single measures). All statistical tests were performed with SPSS, version 15.0 for windows (IL, USA).
