Abstract
Background/purpose
The implantation of bioresorbable scaffolds (BVSs) is an emerging technique in the treatment of coronary lesions and implantation of BVSs is different than that of metallic drug-eluting stents, however, due to different mechanical properties. This investigation focused on procedural and mid-term results and was designed to evaluate whether there is evidence of a learning curve with BVSs and how it might influence the clinical outcome.
Methods/materials
In an all-comers registry, the first 100 consecutive patients were compared with the second 100 patients. Target parameters were major adverse cardiac events (MACEs), including cardiac death, any myocardial infarction, and percutaneous or surgical target lesion revascularization (TLR). Target vessel failure (TVF) comprised cardiac death, target vessel myocardial infarction, and percutaneous or surgical target vessel revascularization (TVR).
Results
Baseline characteristics were not significantly different. Post-dilatation was used significantly more often in the second group (23.8% vs. 50.5%, p < 0.05) as was intravascular imaging (9% vs. 19%, p < 0.05). In-hospital MACEs (2.0% for both groups) and median duration of hospital stay (4 (2–6) days) did not differ significantly. During a follow-up of 210 (155–369) or 200 (176–286) days (p = n.s.) for the first and second groups, respectively, MACE (11.2% vs. 1.1%, p < 0.01), TVF (10.1% vs. 1.1%, p < 0.01), and TVR (9.9% vs. 1.1%, p < 0.05) rates were significantly lower in the second group.
Conclusion
There is evidence of a learning curve. Post-dilatation is most probably associated with an improved clinical result and intravascular imaging might be useful for further improvement.
Highlights
- •
A real world all-comers population treated with BVSs was evaluated.
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The first vs. the second 100 consecutive patients were compared.
- •
The clinical outcome was significantly better in the second group.
- •
Suggested reasons: more frequent use of intravascular imaging and post-dilatation.
- •
Post-dilatation should be performed routinely.
1
Introduction
Bioresorbable scaffolds are a relatively new development in stent technology for the treatment of coronary artery disease. The most widely investigated device is the bioresorbable vascular scaffold (BVS, ABSORB TM , Abbott Vascular, USA), which consists of a poly-L-lactic acid backbone and elutes the anti-proliferative mTOR inhibitor everolimus. Two-randomized controlled trials have demonstrated equal clinical outcome after one year and a similar anti-restenotic effectiveness in comparison to current metallic drug-eluting stents (DESs) . These and other previous encouraging findings in patients with stable coronary artery disease have led to an expansion of their use . There are also some clinical results available that suggest a safe application in patients with acute coronary syndrome . Nevertheless, DESs are still the gold standard according to the existing guidelines . They have been widely investigated in clinical trials and the latest generation demonstrates excellent clinical success that currently outperforms bioresorbable scaffolds .
It must be noted, however, that there are great differences in mechanical properties between the devices. The most obvious difference is that the struts of BVSs have a thickness of 150 μm, whereas DESs of the latest generation have a strut thickness of approximately 65 μm. Moreover, the technique used for implantation of a bioresorbable scaffold is also different, since pre-dilatation is mandatory and post-dilatation is often required. Thus, this new technique and its particularities have to be acquired by the implanting physician.
This investigation was designed to assess and compare procedural parameters of 200 consecutive patients of a real-world, all-comers population and to determine how these affect acute outcome.
2
Methods
2.1
Study design and patient population
To evaluate the potential impact of a learning curve on outcome, we analyzed 200 consecutive patients who underwent BVS implantation at the Department of Cardiology of the University of Giessen, Germany, between September 2012 and September 2013. This cohort was divided into 2 groups: Group A included the first 100 patients and group B the second 100 patients treated consecutively with BVS. Inclusion criteria were any evidence of myocardial ischemia and a vessel diameter between 2.3 and 4.0 mm. Exclusion criteria were a vessel diameter smaller than 2.3 mm or greater than 4.0 mm, lesions that were unsuitable for BVS implantation (e.g. presence of heavy calcification), patients with cardiogenic shock, known allergies or hypersensitivity against BVS components, or dual antiplatelet therapy. Major adverse cardiac events (MACEs) comprised cardiac death, any myocardial infarction, and percutaneous or surgical target lesion revascularization (TLR). Target vessel failure (TVF) included cardiac death, target vessel myocardial infarction, and percutaneous or surgical target vessel revascularization (TVR). Scaffold thrombosis was defined according to Academic Research Consortium (ARC) criteria.
2.2
Device, procedure, and follow-up
The BVS consists of a poly-L-lactic acid (PLLA) backbone with circumferential hoops and cross-linked struts with a thickness of 150 μm. Radiopaque markers are localized at both ends for visualization. The BVS elutes a 1:1 mixture of poly-D, L-lactic acid and the anti-proliferative drug everolimus.
For all patients pre-procedural physical and blood laboratory examinations, 12-lead ECG, transthoracic echocardiography, and previous medical history were captured.
Pre-dilatation was mandatory and therefore a non-compliant balloon was used routinely. Post-dilatation was not performed systematically and the decision was left to the discretion of the implanting physician. When post-dilatation was performed, a non-compliant balloon was utilized. For adequate sizing, quantitative coronary angiography was utilized. Supplementary intravascular imaging including additional sizing was conducted by optical coherence tomography (OCT, ILUMIEN OPTIS, Dragonfly TM , St. Jude Medical, Inc., St. Paul, MN, USA) or intravascular ultrasound (IVUS, Eagle Eye ® Gold, Volcano Corp., San Diego, CA, USA). Intravascular imaging was not mandatory, but highly recommended in complex lesions (B2/C according to ACC/AHA classification). Procedural success was defined as successful implantation of the BVS and an angiographically estimated residual stenosis of ≤ 30%.
Follow-up visits were implemented by telephone and a standardized questionnaire after 30 days, 6 months, and 1 and 2 years. An angiographic follow-up was not mandatory but was performed routinely if medically indicated according to the implanting physician’s discretion.
2.3
Statistical analysis
Continuous variables were presented as mean with standard deviation (SD) or as median and interquartile range. Categorical variables were presented as counts and percentages. To compare the two groups the Mann–Whitney–Wilcoxon U test was utilized for continuous variables, and the Fisher’s exact test or the chi-square test was applied for categorical variables. All tests were two-tailed and a p-value < 0.05 was considered statistically significant.
2.4
Ethics
All patients signed a written informed consent. This investigation was approved by the ethics committee of the University of Giessen, Germany (AZ:246/12). This investigation was performed according to the Declaration of Helsinki.
2
Methods
2.1
Study design and patient population
To evaluate the potential impact of a learning curve on outcome, we analyzed 200 consecutive patients who underwent BVS implantation at the Department of Cardiology of the University of Giessen, Germany, between September 2012 and September 2013. This cohort was divided into 2 groups: Group A included the first 100 patients and group B the second 100 patients treated consecutively with BVS. Inclusion criteria were any evidence of myocardial ischemia and a vessel diameter between 2.3 and 4.0 mm. Exclusion criteria were a vessel diameter smaller than 2.3 mm or greater than 4.0 mm, lesions that were unsuitable for BVS implantation (e.g. presence of heavy calcification), patients with cardiogenic shock, known allergies or hypersensitivity against BVS components, or dual antiplatelet therapy. Major adverse cardiac events (MACEs) comprised cardiac death, any myocardial infarction, and percutaneous or surgical target lesion revascularization (TLR). Target vessel failure (TVF) included cardiac death, target vessel myocardial infarction, and percutaneous or surgical target vessel revascularization (TVR). Scaffold thrombosis was defined according to Academic Research Consortium (ARC) criteria.
2.2
Device, procedure, and follow-up
The BVS consists of a poly-L-lactic acid (PLLA) backbone with circumferential hoops and cross-linked struts with a thickness of 150 μm. Radiopaque markers are localized at both ends for visualization. The BVS elutes a 1:1 mixture of poly-D, L-lactic acid and the anti-proliferative drug everolimus.
For all patients pre-procedural physical and blood laboratory examinations, 12-lead ECG, transthoracic echocardiography, and previous medical history were captured.
Pre-dilatation was mandatory and therefore a non-compliant balloon was used routinely. Post-dilatation was not performed systematically and the decision was left to the discretion of the implanting physician. When post-dilatation was performed, a non-compliant balloon was utilized. For adequate sizing, quantitative coronary angiography was utilized. Supplementary intravascular imaging including additional sizing was conducted by optical coherence tomography (OCT, ILUMIEN OPTIS, Dragonfly TM , St. Jude Medical, Inc., St. Paul, MN, USA) or intravascular ultrasound (IVUS, Eagle Eye ® Gold, Volcano Corp., San Diego, CA, USA). Intravascular imaging was not mandatory, but highly recommended in complex lesions (B2/C according to ACC/AHA classification). Procedural success was defined as successful implantation of the BVS and an angiographically estimated residual stenosis of ≤ 30%.
Follow-up visits were implemented by telephone and a standardized questionnaire after 30 days, 6 months, and 1 and 2 years. An angiographic follow-up was not mandatory but was performed routinely if medically indicated according to the implanting physician’s discretion.
2.3
Statistical analysis
Continuous variables were presented as mean with standard deviation (SD) or as median and interquartile range. Categorical variables were presented as counts and percentages. To compare the two groups the Mann–Whitney–Wilcoxon U test was utilized for continuous variables, and the Fisher’s exact test or the chi-square test was applied for categorical variables. All tests were two-tailed and a p-value < 0.05 was considered statistically significant.
2.4
Ethics
All patients signed a written informed consent. This investigation was approved by the ethics committee of the University of Giessen, Germany (AZ:246/12). This investigation was performed according to the Declaration of Helsinki.
3
Results
3.1
Baseline characteristics
No statistically relevant differences in baseline characteristics were apparent between the two groups. Furthermore, there were no significant differences concerning the patients’ clinical presentation ( Table 1 ).
| Group A (n = 100) | Group B (n = 100) | p-value | |
|---|---|---|---|
| Female gender | 22% (22/100) | 24% (24/100) | n. s. |
| Median age (y, IQR) | 66 (55–71) | 62 (53–72) | n. s. |
| Hypertension | 88% (88/100) | 81% (81/100) | n. s. |
| Diabetes | 31% (31/100) | 34% (34/100) | n. s. |
| IDMM | 35% (11/31) | 21% (7/34) | n. s. |
| Hypercholesterolemia | 60% (60/100) | 50% (50/100) | n. s. |
| Current smoker or h/o smoking | 43% (43/100) | 49% (49/100) | n. s. |
| Pre-disposition for CAD | 22% (22/100) | 28% (28/100) | n. s. |
| CAD | |||
| 1-vessel-disease | 35% (35/100) | 41% (41/100) | n. s. |
| 2-vessel-disease | 45% (45/100) | 34% (34/100) | n. s. |
| 3-vessel-disease | 20% (20/100) | 25% (25/100) | n. s. |
| Previous PCI | 35% (35/100) | 42% (42/100) | n. s. |
| Previous CABG | 9% (9/100) | 3% (3/100) | n. s. |
| Clinical presentation | |||
| STEMI | 21% (21/100) | 21% (21/100) | n. s. |
| NSTEMI | 26% (26/100) | 25% (25/100) | n. s. |
| unstable angina | 14% (24/100) | 16% (16/100) | n. s. |
| stable angina | 38% (38/100) | 38% (38/100) | n. s. |
| other | 1% (1/100) | 0% (0/100) | n. s. |
3.2
Procedural findings
There were no significant differences noted between the groups in median procedure time (group A: 47.5 (36–63) min, group B: 51 (39–69) min), mean contrast volume (group A: 195.0 ± 100.0 mL, group B: 183.2 ± 80.4 mL), or mean X-ray time (group A: 13.7 ± 8.7 min, group B: 13.9 ± 8.1). In both groups the predominant vessel access was radial (group A: 54%, group B: 65%; p = n. s.). A total of 105 lesions were treated in group A and 109 lesions were treated in group B (p = n. s.). There were no statistically significant differences found regarding angiographic lesion characteristics ( Table 2 ).
| Group A (n = 100) | Group B (n = 100) | p-value | |
|---|---|---|---|
| Total number of lesions | 105 | 109 | n. s. |
| Location | |||
| LAD | 38.1 (40/105) | 47.7 (52/109) | n. s. |
| RCX | 33.3 (35/105) | 22.9 (25/109) | n. s. |
| RCA | 28.6 (30/105) | 29.4 (32/109) | n. s. |
| Mean proximal RVD (mm, SD) | 3.0 ± 0.6 | 2.9 ± 0.6 | n. s. |
| Mean distal RVD (mm, SD) | 2.7 ± 0.7 | 2.7 ± 0.6 | n. s. |
| Mean lesion length (mm, SD) | 15.7 ± 10.6 | 18.5 ± 11.6 | < 0.05 |
| Lesion type | |||
| A | 7.6 (8/105) | 1.8 (2/109) | n. s. |
| B1 | 39.1 (41/105) | 42.2 (46/109) | n. s. |
| B2 | 33.3 (35/105) | 27.5 (30/109) | n. s. |
| C | 20.0 (21/105) | 28.4 (31/109) | n. s. |
| Total number of BVSs implanted | 131 | 149 | n. s. |
| Mean number of BVSs per lesion (n, SD) | 1.2 ± 0.6 | 1.4 ± 0.8 | n. s. |
| Mean diameter of BVSs (mm, SD) | 3.1 ± 0.4 | 3.1 ± 0.4 | n. s. |
| Mean BVS ⁎ length per lesion (mm, SD) | 24.4 ± 14.8 | 29.5 ± 20.2 | 0.05 |
| Multiple vessels treated with BVSs | 5% (5/100) | 9% (9/100) | n. s. |
| Additional DES required | 13% (13/100) | 8% (8/100) | n. s. |
| OCT/IVUS use | 9% (9/100) | 19% (19/100%) | < 0.05 |
| Mean number of predilatations per lesion (n, SD) | 1.4 ± 0.8 | 1.4 ± 1.4 | n. s. |
| Mean pressure per predilatation (atm, SD) | 12.9 ± 3.4 | 13.8 ± 5.6 | n. s. |
| Mean implantation pressure (atm, SD) | 11.7 ± 4.0 | 13.3 ± 4.4 | n. s. |
| Post-dilatation performed | 23.8 (25/105) | 50.5 (55/109) | < 0.01 |
| Mean balloon diameter for post-dilatation (mm, SD) | 2.8 ± 0.5 | 3.4 ± 0.5 | < 0.0001 |
| Mean pressure per post-dilatation (atm, SD) | 15.0 ± 4.7 | 16.4 ± 4.2 | n. s. |
| Procedure-related complications | 2% (2/100) | 3% (3/100) | n. s. |
| Median hospital stay (d, IQR) | 4 (2–6) | 4 (2–6) | n. s. |
| Antiplatelet/anticoagulant therapy at discharge | |||
| Aspirin | 99.0 (99/100) | 98.0 (98/100) | n. s. |
| Clopidogrel | 41.0 (41/100) | 41.0 (41/100) | n. s. |
| Ticagrelor | 36.0 (36/100) | 26.0 (26/100) | n. s. |
| Prasugrel | 35.0 (35/100) | 33.0 (33/100) | n. s. |
| Vitamin-K-antagonist | 7.0 (7/100) | 7.0 (7/100) | n. s. |
| NOAK | 6.0 (6/100) | 8.0 (8/100) | n. s. |
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