Atherosclerosis is the major etiological factor
of subclavian artery stenosis (SAS), while less
common factors are embolic occlusions, infections,
radiotherapy, arteritis, and external pressure (i.e.,
tumors and thoracic outlet syndrome).[
4,
5] If there is
a three-vessel or left main coronary artery disease,
the SAS prevalence reaches 5.3%.[
6] Subclavian
steal syndrome results from stenosis or complete
occlusion in the pre-vertebral artery region of the subclavian artery.[
7] This phenomenon is stealing
coronary flow to subclavian artery via LIMA.
In patients undergoing CABG with the LIMA,
long-term patency rates are higher than that of
saphenous vein or radial artery. Therefore, the
use of LIMA is recommended for every suitable
patient.[
8,
9] There should be SSS or occlusion for
coronary steal syndrome with LIMA. Although it is
not common in the society, it can be seen in CABG
patients.[
10] Shadman et al.[
10] reported that the rate
of SSS ranged from 1.9 to 7.1% in four cohorts
(n=4,223). English et al.[
6] also reported that there
was 5.3% SSS in 492 CABG patients undergoing
cardiac catheterization. If peripheral arterial disease
was present, the prevalence of SSS increased up to
11.8%. However, evaluating the LIMA through the
left subclavian artery during coronary angiography
in patients who are considered for CABG surgery is
still controversial.[
7,
8]
Screening for SAS has been advocated by some
authors,[7,11] as CSSS has a potential to cause stable
angina, ST elevation infarction, arrhythmias, or
sudden death resembling to other coronary artery
syndromes.[7,12,13] Vertigo, dizziness, syncope, extremity
hypo-paresthesia, and visual-auditory disturbances may
be the symptoms of CSSS.[1,7,9,12] Physical evaluation is
critical to make a decision for the evaluation of the
LIMA and subclavian artery. Arterial blood pressure
difference between the upper extremities can simply
reveal a SAS.[14,15] However, some limitations, such
as bilateral SAS, arrhythmias, or non-simultaneous
measurement, can lead to a misleading SAS decision.
More objective evaluation should be performed for a
certain diagnosis of SAS.
In two different studies, Lapropoulos et al.[5]
and Tamura et al.[16] showed a very close correlation
between SSS and >20-mmHg pressure difference
between the arms. In the English et al.’s[6] metaanalysis,
a 10-mmHg pressure difference showed a
strong association with SAS (<50%). On the other
hand, Shadman et al.[10] reported that a 15-mmHg
pressure difference was enough for SAS. However,
the main limitation of blood pressure measurement is
that it is an indirect measurement. In our case, there
was a systolic pressure gradient of 25 mmHg and
imaging was needed to confirm the diagnosis of SSS.
Arterial Doppler ultrasonography is one of the most
useful, cost-effective, and sensitive diagnostic tool
for the detection of SAS.[17,18] However, conventional
angiography is still the gold-standard for the diagnosis
in most patients. The CTA is also used quite frequently.
Physical evaluation showed SAS in our patient, and the
diagnosis was confirmed by further examination. In
the event that the reverse flow of LIMA is evaluated,
conventional angiography should be performed for
LAD.
In patients whose anginal complaints begin
or continue after CABG, coronary angiography
is recommended to evaluate the subclavian artery
together with the LIMA-LAD anastomosis. In
patients with stenosis of the proximal subclavian
artery, the LIMA-LAD flow is impaired and ischemia
is detected in the region of LAD artery on myocardial
perfusion scintigraphy.[2,11] The absence of LIMA
flow is seen in subclavian artery occlusion.[4,7,19]
An axillary-to-axillary or carotico-subclavian
bypass are major surgery techniques for the treatment
of SAS.[7,14] Percutaneous transluminal angioplasty
and subclavian artery bypass surgery associated with
stenting are the most commonly used methods in the
treatment of SSS. The PTA is preferred owing to its
low morbidity and shorter hospital stay.[4,20,21] Also,
in the 2017 European Society of Cardiology (ESC)
guidelines, both revascularization options (stenting
or surgery) should be considered and discussed case
by case according to the lesion characteristics and
patient’s risk.[22] In a study, the stroke rate was
2.6% and 2.4% who were treated by PTA and open
surgery, respectively.[23] In such cases, endovascular
treatment is mostly the preferred strategy.[21-23] In a
retrospective study conducted by De Vries et al.,[24]
the success of PTA and stenting was 93%, and the
patency rate was 93% after three years. Although the
carotico-subclavian artery bypass surgery method is relatively less frequently performed, the success rate
was reported as 98%, with a 10-year patency rate of
around 95%.[19] In the study by Jahic et al.,[25] PTA
treatment was performed in 22 of 26 patients, and
a 100% patency rate was achieved within one-year
follow-up. As a result of this study, PTA treatment
was suggested for those with subclavian stenosis, while
surgical treatment was recommended for those with
obstruction.[25]
In recent years, new laser cutting balloon
therapies and drug-coated balloon therapies have
been developed.[9,26] Self-expendable stents have
more stronger radial force and easier to deploy in
more calcific lesions.[9,25] Medical therapy after PTA
or surgery is similar. Antiaggregant-based therapy
(acetylsalicylic acid and clopidogrel) is the mainstay,
although patient-based individualized therapy is
always the primary preference. Anticoagulant therapy
can be prescribed in cases who has a concomitant atrial
fibrillation or a hypercoagulation state.[9,19,27] In this
case, we preferred PTA treatment, due to the advanced
age of the patient and the presence of a stenosis rather
than a complete occlusion of the subclavian artery.
Additionally, the lesion was deemed suitable for a
percutaneous intervention.
The literature consists controversial issues. First
and more controversial of them is the performance
of a subclavian artery and LIMA imaging during
preoperative angiography. The second issue is using the
LIMA in patients receiving a surgical or endovascular
intervention for SAS.[4,24] However, in a study, CABG
with LIMA was performed at the same day of
successfully treated SAS patients and the authors
used acetylsalicylic acid after CABG.[28] The third
is the treatment selection: surgery versus PTA. The
literature review reveals that patient-based selection is
more important and both surgery and PTA treatment
are safe.[4,7,22]
In conclusion, although coronary SSS is rare, it
is a critical syndrome due to its possible role in the
disruption of myocardial perfusion and development
of angina pectoris and symptoms of dyspnea.
Percutaneous treatment is safe and effective in eligible
cases. We recommend physical examination of SAS
for CABG candidates preoperatively and angiographic
evaluation of the subclavian artery in patients who has
a concomitant peripheral arterial disease.
Declaration of conflicting interests
The authors declared no conflicts of interest with respect
to the authorship and/or publication of this article.
Funding
The authors received no financial support for the research
and/or authorship of this article.