Abstract
Background
Direct coronary stenting is a validated therapeutic option for coronary lesions. We studied the feasibility of direct deployment with a bioresorbable vascular scaffold (BVS) in acute coronary syndrome (ACS).
Methods
Demographic, procedural, and survival data were obtained for patients who had direct scaffold deployment with BVS from 1 May 2013 to 1 April 2014.
Results
We performed a retrospective review of nine patients which included eight patients having ST-elevation myocardial infarction. There were no cases of worsening coronary flow, scaffold thrombosis, target lesion revascularization or death up to 30 days post intervention.
Conclusion
Direct BVS deployment in ACS appears safe and feasible.
Highlights
- •
Limited evidence for use of bioresorbable vascular scaffold (BVS) in ACS patients.
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Eight patients had acute STEMI and underwent primary PCI with BVS.
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No cases of worsening flow, scaffold thrombosis, TLR or death to 30 days post PCI.
- •
Direct BVS deployment in ACS appears safe and feasible.
1
Introduction
The long-term safety of the drug eluting stent (DES) , in particular the occurrence of very late stent thrombosis, raises concern over permanent metallic stenting in coronary arteries. The concept of the “short-term” vascular scaffold may offer a viable solution by providing temporary radial support by scaffolding that later becomes fully resorbed via endogenous cellular and metabolic pathways . The everolimus-eluting bioresorbable vascular scaffold (BVS) has shown reasonable safety and efficacy in short-term follow-up in patients with de novo coronary lesions after appropriate lesion preparation . There is limited evidence however, for the use of BVS technology in patients with acute coronary syndrome (ACS) . The first case series of BVS use in the setting of ST elevation myocardial infarction was published in 2013 . More recently, a 1-year outcome study demonstrated, similar outcome with BVS, DES or bare metal stents (BMS) .
In the setting of ACS, direct stenting has been advocated as a potentially preferred technique where clinically feasible. This technique has been utilized with metallic stents in appropriately selected lesions in patients with stable coronary artery disease , non ST-elevation ACS , and ST-elevation myocardial infarction (STEMI) . Direct stenting may reduce ischemic time, distal edge stent dissection, and thrombus and/or plaque fragmentation with distal migration. Most importantly, it may also provide superior myocardial perfusion with less distal embolization and microvascular dysfunction with higher frequency of TIMI 3 flow post revascularization . These attributes make this technique appealing in the setting of ACS, particularly in primary percutaneous coronary intervention (PCI) for STEMI. It is plausible that direct scaffold deployment with BVS would be technically feasible in select patients . Our case series aims to report the safety, feasibility, and short-term performance of BVS deployed without pre-dilatation for ACS in a tertiary academic center in Ontario, Canada.
2
Methods
Thirty-seven patients underwent PCI with BVS implantation from June 2013 to March 2014, of which 30 had ACS. Baseline demographics, ECG and cardiac biomarker data, coronary angiography, BVS deployment details, and use of adjunctive coronary imaging were recorded. American College of Cardiology (ACC) Guidelines for Coronary Angiography was used to classify lesion type . Oral antiplatelet therapy, intravenous unfractionated heparin and/or glycoprotein infusion were administered according to consensus guidelines. The scaffold used at our center, Absorb (Abbott Vascular, Santa Clara, CA, USA) is a second generation BVS composed of a poly L-lactide (PLLA) backbone with a strut thickness of 150 μm. It is coated with a polymer of poly DL-lactide (PDLLA) and the mammalian target of rapamycin (mTOR) inhibitor everolimus, which is slowly released over 30 days. Two platinum markers at each scaffold end aid fluoroscopic identification. Scaffold degradation begins by hydrolysis of esterified bonds by water, which generates lactic acid that is then rapidly metabolized through the Kreb’s and pyruvic acid cycles.
Device success was defined by fluoroscopic evidence of ≤ 20% residual stenosis of the target lesion covered by the BVS. Procedural success was defined additionally by the lack of major peri-procedural coronary complications. Major adverse cardiac events included cardiac death, scaffold thrombosis or clinically driven target lesion revascularization at 30 days and 3 months. Descriptive statistics were provided for all variables. Continuous variables were presented as mean and standard deviation or as median and interquartile range when appropriate, whereas categorical variables were presented as counts and percentages.
This study has been approved by Western University’s Research and Ethics Board (REB).
2
Methods
Thirty-seven patients underwent PCI with BVS implantation from June 2013 to March 2014, of which 30 had ACS. Baseline demographics, ECG and cardiac biomarker data, coronary angiography, BVS deployment details, and use of adjunctive coronary imaging were recorded. American College of Cardiology (ACC) Guidelines for Coronary Angiography was used to classify lesion type . Oral antiplatelet therapy, intravenous unfractionated heparin and/or glycoprotein infusion were administered according to consensus guidelines. The scaffold used at our center, Absorb (Abbott Vascular, Santa Clara, CA, USA) is a second generation BVS composed of a poly L-lactide (PLLA) backbone with a strut thickness of 150 μm. It is coated with a polymer of poly DL-lactide (PDLLA) and the mammalian target of rapamycin (mTOR) inhibitor everolimus, which is slowly released over 30 days. Two platinum markers at each scaffold end aid fluoroscopic identification. Scaffold degradation begins by hydrolysis of esterified bonds by water, which generates lactic acid that is then rapidly metabolized through the Kreb’s and pyruvic acid cycles.
Device success was defined by fluoroscopic evidence of ≤ 20% residual stenosis of the target lesion covered by the BVS. Procedural success was defined additionally by the lack of major peri-procedural coronary complications. Major adverse cardiac events included cardiac death, scaffold thrombosis or clinically driven target lesion revascularization at 30 days and 3 months. Descriptive statistics were provided for all variables. Continuous variables were presented as mean and standard deviation or as median and interquartile range when appropriate, whereas categorical variables were presented as counts and percentages.
This study has been approved by Western University’s Research and Ethics Board (REB).
3
Results
3.1
Patients
Nine (mean age 55.6 ± 12.4 years) of 30 patients with ACS were treated with BVS deployment without pre-dilation. Less than half were female, diabetic, and actively smoking (all 44%), whereas 56% had hypertension and 67% had dyslipidemia ( Table 1 ).
| Demographic data | Total BVS (n = 21) | Direct stent BVS (n = 9) |
|---|---|---|
| Age (years) | 56.6 | 55.6 |
| Female gender | 23.8% (5) | 44% (4) |
| Diabetes mellitus | 28.6% (6) | 44% (4) |
| Current smoker | 28.6% (6) | 44% (4) |
| Dyslipidemia | 71.4 (15) | 67% (6) |
| Hypertension | 71.4% (15) | 56% (5) |
| CABG | 4.7% (1) | 0 |
| Vessels involved | ||
| LMS | 4.7% (1) | 0 |
| LAD | 71.4% (15) | 44.4% (4) |
| Proximal LAD | 14.3% (3) | 25% (1) |
| Mid to distal LAD | 57.1% (12) | 75% (3) |
| LCX | 14.3% (3) | 11.1% (1) |
| RCA | 9.5% (2) | 44.4% (4) |
| ACS presentation | ||
| STEMI | 33% (7) | 89% (8) |
| NSTEMI | 66.7% (14) | 11% (1) |
3.2
Angiographic data
Eight patients had acute STEMI and underwent primary PCI. The infarct related artery was often the left anterior descending or right coronary artery (44%), and less often the left circumflex (11%). At index angiography, one-third of patients had no coronary flow in the infarct related artery and 55% had significant thrombus load. Most lesions were ACC type-B with relatively low median SYNTAX scores ( Table 2 ). Aspiration thrombectomy and OCT-guided PCI ( Figs. 1 and 2 ) were performed in 4 and 3 patients, respectively. Mean BVS length per-lesion was 19.6 ± 5.8 mm and mean BVS diameter per-lesion was 3.33 ± 0.11 mm. Post-dilatation was performed in all “direct” scaffold procedures using a mean inflation pressure of 16.4 ± 3.2 atm. There was no side branch occlusion in any of the patients who had bifurcation lesions ( Table 2 ).
| Angiographic data | Total BVS (n = 21) | Direct stent BVS (n = 9) |
|---|---|---|
| Pre-procedure TIMI flow | ||
| 0 | 28.6% (6) | 33.3% (3) |
| 1 | 0 | 11.1% (1) |
| 2 | 9.5% (2) | 22.2% (2) |
| 3 | 61.9% (13) | 33.3% (3) |
| Lesion characteristic | n = 32 | n = 11 |
| Predominant thrombus | 25% (8) | 54.5% (6) |
| Predominant calcification | 6.3% (2) | 0% |
| Predominant plaque disease | 68.8% (22) | 45.5% (5) |
| Thrombus burden at culprit | ||
| 0 | 23.8% (5) | 22.2% (2) |
| 1 | 28.6% (6) | 11.1% (1) |
| 2 | 4.8% (1) | 11.1% (1) |
| 3 | 19% (4) | 11.1% (1) |
| 4 | 9.5% (2) | 11.1% (1) |
| 5 | 14.3% (3) | 33.3% (3) |
| SYNTAX score (median) | 15 | 7 |
| ACC lesion type | N = 32 | N = 11 |
| A | 9.4% (3) | 9.1% (1) |
| B | 71.9% (23) | 72.7% (8) |
| C | 18.8% (8) | 18.2% (2) |
| Small side branch (bifurcation lesions) | 42.8% (9) | 44.4% (4) |
| Final TIMI flow 3 in side branches | 100% | 100% |
| Procedural data | ||
| Manual thrombectomy | 20% (2) | 44.4% (4) |
| Post-dilatation | 68.7% (22) | 100% (9) |
| Total number of scaffolds (n) | 32 | 11 |
| Mean scaffolds per-patient (n) | 1.52 | 1.22 |
| Mean scaffold length per-lesion (mm) | 20.5 ± 5.9 | 19.6 ± 5.8 |
| Mean scaffold diameter per-lesion (mm) | 3.03 ± 0.43 | 3.33 ± 0.11 |
| Mean pressure (atm) | 16.6 ± 3.5 | 16.4 ± 3.2 |
| Post-BVS TIMI flow | ||
| 0 | 0 | 0 |
| 1 | 0 | 0 |
| 2 | 0 | 11.1% (1) |
| 3 | 100% (21) | 88.9% (8) |
| Post-BVS implant residual diameter | ||
| > 20% | 0 | 0 |
| < 20% | 100% (30/30) | 100% (9/9) |
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