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(2.5%). The rate of ST was 2 cases (2.5%) including: one case of definite stent thrombosis at 34 months after intervention and one sudden death at 2 weeks after intervention was determined as possible stent thrombosis (1.25%). There was no case of a stroke.
3.3. LATE LUMEN LOSS
A total of 49 cases of coronary angiography at follow up (61.3%) after 15.57.3(months): The lesion angulation was 29.2614.39 (degrees). MLD was 3.100.68 (mm). % DS was 10.7417.51 (%). There were 4 patients (8.2%) significantly restenosis> 50% of RD. There were 3 cases (6.1%) with localized stenosis and one case (2.1%) with diffuse stenosis. Significantly restenosis:
100% was ACS, 100% after 12 months, 75% anterior ventricular artery, 50%
asymptomatique. LLL was 0.250.44 (mm); longterm LLL are superior in compare with midterm LLL.
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When comparing between the young patients (<65 years) and the elderly (≥ 65 years), the young patients showed that the results of immediate intervention on QCA were better with the acute lumen gain (2.970.07mm compared to 2.780.06mm; p = 0.03) and less change in lesion angulation (4.590.5 degrees compared to 6.760.6 degrees; p = 0.008). However, %DS of young group's residues was higher (3.740.6% compared with 2.150.3%; p = 0.02). Moreover, the DoCE of the two age groups was similar.
7.2.2. Gender
Comparison of the results of immediate intervention between the two sex groups showed that the change in lesion angulation immediately after intervention in men was less than that of women (4.96 degrees compared to 6.91 degrees; p = 0.027). However the DoCE between the two groups was similar.
Baquet's research showed that women had the TLR (7.5% versus 12.4%; p = 0.51) and ST (1.2% vs 2.7%; p = 0.20) tended to be lower but not statistically significant compared to men. And women are considered to be a protective factor in BVS, possibly due in part to a less complicated level of coronary lesions. In contrast, the IT-DISAPPEARS study found that women are independent prognostic factors that increase DoCE in patients with long and / or diffuse lesions. In the AIDA study, there was no difference in DoCE and ST between Absorb and EES groups in female patients. However, in male patients, the incidence of ST in the Absorb group was significantly higher and the risk of DoCE was also bigger.
7.2.3. Diabetes
The rate of diabetes in our study was 22.5% lower than some other studies but higher than the FRACE ABSORB study of 16.0%. We did not see any difference in the level of angina, dyspnea, nor results of coronary intervention and DoCE after follow-up. Diabetes is a strong independent predictor of intervention events, due to increased platelet aggregation, increased inflammation and endothelial dysfunction, and stimulation of proliferation of vascular smooth muscle cells. In contrast, coronary artery disease was the cause of 80% of deaths and 75% of hospitalization in patients with diabetes.
7.2.4. Clinical context
17 7.2.4.1. Acute coronary syndrome
Acute coronary syndrome accounted for 60% of the study patients. This rate was similar to some studies. When compared with stable angina group, acute lunen gain after intervention in ACS group was higher (2.970.06 mm compared to 2.77 0.07 mm; p = 0.048). However, residual stenosis and lesion angulation change did not differ between the two groups (p> 0.05). Clinically, the rate of complete relief of angina was less (72.9% compared to 96.9%; p = 0.006); however, DoCE had no difference between the two groups after follow-up. According to studies, in ACS, the RD of the culprit lesion is quite large and soft atherosclerotic lesions help BVS for better apposition. A meta-analysis of 2318 ACS patients who had BVS, medium-term follow-up time, averaging 9.5 months showed a higher incidence of ST (2.3% vs 1.08%; p = 0.03), TLR was higher (3.5% compared to 2.5%; p = 0.04) when compared with EES group. In another study, however, ACS was considered to be a significant prognostic factor that reduced DoCE.
7.2.4.2. Myocardial infarction
The percentage of patients with MI was 20%, of which 5% was NSTEMI, and 15% was STEMI. This rate is quite high in general studies of BVS, not including separate studies on patients with acute coronary syndrome or myocardial infarction. The MI group had better results than the non-MI group in the results of intervention according to QCA with acute lumen gain right after intervention was better (3.210.09mm compared to 2.810.05mm; p <0.001).
However, %DS and lesion angulation change did not differ between the two groups (p> 0.05). Theoretically shows that acute MI is a group of pathologies that could benefit from BVS. There are several possible explanations for this phenomenon: lesions are often proximal large vessel, less calcified, and thin cap with soft necrosis. So there is no need to carefully prepare the lesion. A meta-analysis of STEMI showed that DoCE after 1 year was similar between Absorb and EES (5.3% compared to 5.6%; p = 0.91). The TROFI study showed that the endothelial healing after STMEMI intervention was better with Absorb than EES.
7.2.5. DAPT use
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DAPT use at 12 months of our study was quite low (40%), although a high proportion of ACS (60%) required DAPT adherence to more than 12 months in accordance with ESC and AHA / ACC guidelines at that time. Studies designed later in addition to Absorb II with DAPT use time required at least 6 months, the remaining Absorb III, Absorb China, Absorb Japan, etc. are required to use DAPT for at least 12 months. However, the above studies were started from 2016 onwards, when the results of the previous studies showed high incidence of ST in Absorb tends to be higher than DES, so it is recommended with longer and stricter DAPT usage. Updated instructions on ESC 2017's DAPT time for BVS for both stable angina and ACS are at least 12 months. In clinical practice, after recommending BVS, experts recommend using DAPT for at least 12 months, however, in some complex cases (lesions of type B2 / C,> 1 BVS, etc.) can be used for up to 24 months or more if there is no high risk of bleeding.
7.2.6. Coronary angiography
In our study, the average procedure time was 41.013.0 minutes. This time is similar to the Absorb III study was (4223 minutes). The reason for increasing the time of Absorb interventions according to many studies is that lesions often have to be prepared, stent gradually pressurized in a separate process (2atm / 5 seconds), post dilatation, special techniques like PSP and specifically for invasive imaging diagnostics (IVUS, OCT).
The average amount of contrast used was 151.0 44.03 ml. The reason is that Absorb stent is not radiopaque so it is harder to identify than DES.
The most common culprit in our study was the LAD (64.6%), which is quite high compared to other studies. Studies have shown that one of the preferred lesion sites to use BVS over BMS is middle LAD. The reason for this is that in the long term it is possible to release the metal frame and provide a place CABG in the future. However, LAD is also an independent prognostic factor that increases DoCE.
The coronary artery lesion is only a lesion, on vessel, the diameter of the missing vascular part of our study is much larger, but the length of the lesion is longer than that of other Absorb studies. However, complex lesions (B2 + C) is
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lower than other studies. Studies show that small coronary artery is an independent prognostic factor of MACE. Therefore, the recommendation of Abbott (United States) is the contraindication to use Absorb stent for small coronary arteries with a reference diameter <2.5mm. Long lesion, complex and multivessel lesions (B2 + C), are also independent factors that increase MACE.
In our study, the percentage of pre-dilatation balloon (97.5%), post-dilatation balloon (98.8%) and the use of PSP technique (62.5%) were higher than those of other studies, including patients with ACS or MI. Well-prepared balloon play an important role in reducing stent recoil after intervention. Residual stenosis
≥20% after predilatation balloon increases the acute recoil after intervention of BVS while metal stent do not have this phenomenon. Using a balloon is more suitable for vascular physiology but also more technically safe. PSP helps for optimal expansion of the BVS and helps reduce the risk of ST and long-term events.
Table 4.2. Coronary angiography results
Parameter Our
study
Absorb China
Absorb Japan
Absorb III
LAD lesion (%) 63.8 55.4 46.2 44.5
Bifurcation lesion (%) 47.5 50.2 0 0
A + B1 type lesions (%) 80 25.1 24 31.3
RD (mm) 3.53 2.81 2.72 2.67
MLD (mm) 0.54 0.98 0.96 0.92
%DS 88.5 65.3 64.6 65.3
Lesion length (mm) 21 14.1 13.5 12.6
Pre-dilatation balloon (%) 97.5 99.6 100 100 Post-dilatation balloon (%) 98.8 63 82.2 65.5
PSP technique (%) 60.0 78.2
Procedure time (minutes) 41 42.2
7.3. EARLY AND MID-TERM OUTCOMES 7.3.1. Early outcomes
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Clinical device success was 97.5%. This ratio is similar to the study of Absorb stent with other large sample sizes. In our study, the lesions were mainly A + B1 tip (80% used the technique of applying one stent to the whole lesion so the success rate was high. The clinical procedure success rate was 96.25%, quite similar to the studies with patients with simple lesions. Periprocedural DoCE is the MI related to the target vessel in the mid-LAD bifurcation lesion are all independent prognostic factors of the MI. The angle lesion decreased after intervention but the degree of reduction was lower than in the Absorb studies.
If the lesion angulation is ≥33.5 degrees (about 40.3% of the patients), and the change of the lesion angulation is above 9.1 degrees after intervention is thought to be an independent predictor of ISR. The acute lumen gain was higher, %DS was lower and post-procedural MLD was bigger than in other BVS studies, partly due to the large reference diameter, the more common PSP use and the hight incidence of ACS in our study (60%).
Table 4.3. Procedural results compared with other studies
Parameter Our
study
Absorb China
Absorb Japan
Absorb II
%DS 3.01 12.2 11.8
Acute lumen gain (mm) 2.89 1.51 1.46 1.15
Absolute recoil (mm) 0.15 0.19
7.3.2. Mid-term outcomes
There are 79 patients at 12 months follow-up: angina free is 93,6%, higher than in Absorb III. Mortality is 1.25%, same as Absorb III. ST is 1.25%, same as Absorb III. DoCE were 3.75% same as Absorb China (3.4%), Absorb Japan (4.2%) but less than Absorb III (7.8%). A number of meta-analyzes including evaluations of outcomes in the first year after stenting indicated that DoCE was equivalent between Absorb and EES, although Absorb stent thrombosis was higher. This can be explained by in our study, 100% of patients have only 1 lesion on a single coronary artery. Coronary artery lesions only had to have 1 Absorb stent while the above studies had a certain overlapping stent rate.
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Moreover, the reference diameter of coronary artery was larger (3.53mm), the acute lumen gain was higher (2.89mm), the %DS after intervention was low (3.01mm).
7.3.3. Continued follow-up
All 79 patients in our study were followed up to the end of the study with an average follow-up time of 16.937.01 (months). Recurrent angina show up to 24,1%. DoCE were 7.5% higher than DoCE at 12 months. All ID-TLR are after 12 months with 2,5%, in-stent ST is 2,5%. As many studies with Absorb stent show that DoCE increase singnificantly after 12 moths in compare with DES especially ST. That is because the process of absortion completely between 2 and 4 years leads to late recoil, fracture of the stent. That why recommendation not to use Absorb in practice nowaday.
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Table 4.4. Midterm clinical outcomes compared with other studies
Parameter Our
study
Absorb China
Absorb Japan
Absorb III
Device success 97.5 98 98.9
Procedure success 96.25 97 97.7 94.6
Recurrent angina (%) 6.4 18.3
Mortality (%) 1.25 0 0.8 1.1
ID-TLR (%) 0 2.5 2.6 3.0
ST (%) 1.25 0.4 1.5 1.5
DoCE (%) 3.75 3.8 4.2 7.8
DAPT 12 months (%) 57 100 100 100
7.4. LATE LUMEN LOSS BY QCA.
The lesion angulation over time increased more than immediately after the intervention 3,553,72 (degree), like the value as before the intervention. The change is statistically significant with p <0.001. Thus, over time, the lesion angulation tends to increase again, helping to preserve the coronary morphology as before. Studies with BVS in general and Absorb in particular, the lesion angulation over time will return to near-pre-intervention values, helping to preserve coronary morphology, the potential to reduce clinical events.
The assessment on QCA shows that late lumen loss (LLL) corrected was 0.250.44 (mm). The results of LLL in our study were similar to those of similar studies. With the average time of 15.57.32 (months) from the time of intervention to the time of coronary artery repression, LLL correlated linearly with the time of stenting. The correlation coefficients were calculated as r = 0.332 (Spearman’s correlation) and p = 0.021. Evaluating a number of studies with patient subjects and lesion characteristics quite similar to our study. As the ABSORB Cohort B study had a follow-up time of 2 years, the LLL was 0.250.22 (mm). The study of Khamis on de-novo lesion, one vessel, one BVS but the lesion is shorter than that in our study, LLL after a year of follow-up is 0.270.20 (mm) Another study also showed that the LLL after one year was 0.380.9 (mm). LLL significantly increase from 16 months after intervention.
Table 4.5. Late lumen loss compared with other studies
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Parameter Our study Absorb China
Absorb Japan
Absorb II Late lumen loss
LLL (mm)
0.25 (15.5 months)
0.23 (12 months)
0.19 (13 months)
0.37 (3 years)
In our study, several factors related to LLL as other studies were also evaluated as: reference lumen diameter, residual stenosis after pre-dilatation, residual stenosis after post-dilatation, PSP technique or other factors such as diabetes, hypertension. However, we did not find any correlation of these factors with late lumen loss. In addition, no association was found between LLL and cardiovascular outcomes such as DoC or ST.
CONCLUSION
From the research results, we have some conclusions:
1. Assessment of the early and medium-term results (after 12 months) of Absorb stent (BVS) in coronary intervention:
The early outcome (immediately after the intervention): Clinical device success is 97.5%; Clinical procedure success is 96.25%. Peri-procedural device-oriented composite endpoint (DoCE) is 1.25% with 1 peripocedural myocardial infarction case. Acute change in lesion angulation, with decrease in angulation, is 5,593,72 degree. Independent predictors of smaller change in angulation are: male sex and <65 years. Incidence of side branche occlusion is 0%. Acute absolute recoil of the stent was 0,150,11 mm. Acute lumen gain is 2.890.05mm. Independent predictors of higher acute lumen gain are: ACS, MI and age <65years.
The mid-term outcome at 12 months: Event-free of angina is 93.6%.
Device-oriented composite endpoint (DoCE) is 3.75%, including:
cardiovascular death 1.25%, target vessel – myocardial infarction (TV-MI) is 2.5%, ischemia-driven target lesion revascuralization (ID-TLR) is 0%. ST is 1.25%.
2. Assessment of the late lumen loss with Absorb stent (BVS) by QCA: