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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 27, No 6, November/December 2016
348
AFRICA
Discussion
Our study shows that BVS implantation in CTO lesions appeared
to be effective and safe in terms of acute procedural and short-
term clinical follow-up results.
Theoretically, complete resorption of BVS, which is used
for treating complex and calcific lesions, such as CTOs, seems
to be advantageous. Lack of a metallic cage in these lesions
can decrease the risk of restenosis, especially in the long term.
Restoration of the vessel’s vasomotor functions may be easier
with BVS implantation than with metallic stents.
Since patients with complex lesions such as CTOs have a
greater risk for future CABG surgery, resorption of BVS in the
treated segment may facilitate the performance of future graft
anastomosis. However, in practice, the real effectiveness and
safety of the use of BVS in CTO lesions are unclear and long-
term clinical results are lacking. A few records and case reports
have been published in the literature which analyse the role of
BVS implantation in CTO lesions.
14-17
The baseline characteristics of our patients were similar
to those in previous BVS studies including patients with
CTO lesions.
14-16
In addition the cardiovascular risk profile of
our patients was high and parallel with real-life records that
investigate the effect of regular PCI procedures in CTO lesions.
Our mean BVS length was shorter than in previous studies.
14,15
Most of our CTO lesions were within the treatable length of
one BVS. Only 11 patients were treated with double BVS and
no patients were treated with more than two BVSs. Although we
had similar TLR rates and short-term clinical results with the
BVS CTO studies, which included longer CTO lesions treated
with a larger number of BVSs, studies with longer follow up
beyond the resorption period of BVSs are needed in order to
clearly determine the effect of scaffolds.
It is known that longer CTOs treated with a larger number
of metallic stents have a greater risk of restenosis and worse
clinical outcomes during follow up.
18,19
Currently, we do not
know whether complete resorption of the implanted scaffolds
eliminates the risk of restenosis in long CTO segments in the
long term.
Although BVS has thick struts (150 µm), a low crossing
profile and less distensibility, our procedural success rate was
100% in our patient group. The main reasons for procedural
success are effective dilatation after wiring the lesions, exact
scaffold sizing with the aid of quantitative coronary angiography
(QCA) measurements, and a high rate of post-dilatation. Lesion
preparation before BVS implantation is a crucial factor, especially
for CTO lesions.
Since a non-compliant balloon (NCB) reduces the procedure
time compared with the compliant balloon,
20
and is advised by
many experienced centres,
21,22
we preferred NCB for effective
dilatation after pre-dilatation with lower-profile balloons. Also,
a cutting balloon and rotablator can be used if needed. We
performed post-dilatation in almost every lesion, mainly with a
non-compliant balloon. We did not use balloons that had a size
of more than 0.5 mm larger than the implanted BVS diameter.
Post-dilatation with an inappropriate size of balloon can lead to
fracture of the BVS in heavily calcific CTO lesions. We did not
experience BVS fracture in our patient group.
Despite our high procedural success rate, implanting BVS
in CTO lesions should be reserved for less complex CTO
lesions, since experience is still limited. The J-CTO score, which
characterises lesion complexity, could be a useful tool for
decision making on indication. According to previous studies,
CTO lesions that have a score of more than three (very difficult
category) are associated with an unsuccessful procedure.
14,23
The
majority of our lesions were within the intermediate category
according to the J-CTO score (56%). More complex lesions with
a higher J-CTO score could affect procedural success and clinical
outcomes.
During CTO procedures, jailing of the major side branches
could be a problem, affecting the success of the procedure.
14,15
Complete resorption of the BVS at the site of the bifurcation
could lessen the effect of jailing and help return the side branch
to normal vasomotor function. In our study, six side branch
occlusions and four side branch narrowings were observed
because of scaffold jailing. All of these lesions were treated with
a provisional strategy with final kissing balloon dilatation.
Intravascular ultrasound (IVUS) and optical coherence
tomography (OCT) are very valuable tools for evaluating the
apposition of BVS during implantation.
12
Not using IVUS
or OCT is a limitation of our study but we had used QCA
measurements for exact sizing of the BVS.
Since our study was non-randomised and lacked a control
group, one should be cautious when interpreting the clinical
data. A randomised study with a larger number of patients
would be more valuable for evaluating the clinical outcomes.
Our clinical follow-up results are too limited to evaluate the real
clinical effectiveness of the use of BVS in CTO lesions. One year
is a short follow-up period and cannot answer the question as
Table 2. Procedural characteristics
Procedure
n
= 41 patients
n =
52 BVS (%)
BVS diameter, mm
2.8
±
0.29
BVS length, mm
25.6
±
4.2
Post-dilatation
40 (97.5)
Post-dilatation with NCB
38 (92.6)
RVD post-procedure, mm
2.8
±
0.25
MLD post-procedure, mm
2.5
±
0.25
Side-branch occlusion
6 (11.5)
Side-branch narrowing
4 (7.6)
CTO technique
Antegrade
36 (87.8)
Retrograde
5 (12.1)
Microcathater use
13 (31.7)
Procedure time, min
92
±
35.6
Fluoro time, min
20.2
±
4.8
Contrast volume, ml
146.6
±
26.7
BVS: bioresorbable vascular scaffold, CTO: chronic total occlusion, MLD:
minimal lumen diameter, NCB: non-compliant balloon, RVD: reference vessel
diameter.
Table 3. Clinical outcomes
One-year outcome
n
= 41 patients (%)
Death
–
Myocardial infarction
1 (2.4)
Angina
11 (26.8)
Coronary artery bypass graft
–
Target-lesion revascularisation
1 (2.4)
Target-vessel revascularisation
5 (12.2)