1. What is a coronary chronic total occlusion?
A CTO is defined as a total occlusion (100%) of a coronary artery without antegrade blood flow, of
at least three months duration. This condition is present in 15-20% of patients with coronary artery
disease and in 50-70% of patients who underwent coronary artery bypass surgery. Usually,
collateral branches, originating from the same or other coronary arteries, maintain the blood flow to
the heart muscle (myocardium), but in almost all patients the presence of a CTO leads to a reduced
supply of oxygen and nutrients to the myocardium (myocardial ischaemia) and is therefore
associated with an increased risk of mortality, life-threatening arrhythmias and symptoms such as
chest pain (angina), shortness of breath or increased fatigability.
2. How is CTO recanalisation performed?
Percutaneous coronary intervention (PCI) of a CTO is a procedure that consists of crossing the
occlusion by using special guidewires, over which balloon catheters can be advanced to dilate the
occluded segment, allowing blood to flow through it again. Depending on the site of the occlusion,
its length, the presence of collateral branches, tortuosity, calcifications, and other anatomical and
clinical features, crossing the occlusion can be more or less difficult. Its duration is therefore
variable but generally a procedure to cross a complete occlusion requires more time than a PCI of a
non-occluded vessel, sometimes up to 90-120 minutes or more. In most cases it is necessary and
desirable to use two different arterial vascular accesses, which, at the cardiologist's discretion, may
be in the groin (femoral), wrist (radial) or, more rarely, in the arm (brachial). The occlusion can be
crossed through the vessel upstream of the occlusion (antegrade crossing) or downstream of the
occlusion through collateral branches originating from other coronary arteries or, if they are present
and approachable, through bypass grafts (retrograde crossing). In both cases the CTO can be
crossed by sliding inside the occlusion itself or through the area immediately around the occlusion
(subintimal space), sometimes with the assistance of special catheters which allow the re-entry in
the vessel lumen. When the CTO is heavily calcified, it may be appropriate to use techniques which
fragment or crack the calcium to facilitate the dilatation of the vessel: these techniques include the
use of particular balloon catheters generating acoustic waves (intravascular lithotripsy), or rotating
burrs (rotational and orbital atherectomy). After dilatation, it is almost always necessary to implant
one or more metal prostheses that look like small hollow tubes, called stents, to reduce the risk of
re-occlusion of the vessel. Stents are made of inert metal (stainless steel-based alloys) and therefore
will not be rejected or cause allergies or tumours. Stents are embedded at high pressure into the wall
of the artery: they will not move after deployment. Newer generation stents elute a drug in order to
reduce the proliferation of tissue lining the artery wall, thus reducing the risk of the coronary artery
re-closing (restenosis). After recanalisation of a CTO, particularly if stents are implanted, the
patient is required to take daily medication to make the platelets less active (normally aspirin in
combination with other antiplatelet agents). Dual antiplatelet therapy should be continued for a time
depending on the clinical complexity of the coronary disease, patient's other co-pathologies and the
number and length of stents implanted. A single antiplatelet drug must then be continued life-long.
Let us know if you have allergies to aspirin or history of major bleedings in the past.
3. Benefits of a CTO recanalization
CTO recanalization restores normal blood flow in the occluded coronary artery. This will allow
your heart to receive adequate blood flow both at rest and during physical exertion, resolving
myocardial ischaemia and reducing episodes of angina and shortness of breath and improving your
quality of life and exercise capacity, as demonstrated in hundreds of patients enrolled in randomised
controlled clinical trials.
4. Expectations and risks
CTO recanalisation represents one of the most complex percutaneous revascularisation procedures,
but in recent years the operators’ increased experience and the refinements of the technique,
together with the availability of dedicated high-performance equipment, resulted in an overall
success rate of approximately 70-95%. The complexity of the procedure may lead to increased Xray exposure time and higher doses of radiological contrast medium. To avoid these risks, when
predetermined safely threshold of X-ray dose and contrast use are reached, it is general practice to
interrupt the procedure without completing the recanalisation of the vessel (investment procedure).
Besides the general complications possible for all PCIs some complications are more specific of
5. CTO recanalisation. They include:
- Coronary perforations (2.5-8.8%): they are mostly benign and, when it is only the wire
piercing the occluded segment, the perforation only requires a reassessment of the strategy
with the use of an additional antegrade wire (parallel wire technique) or a switch to
retrograde. Other larger perforations may require a prolonged balloon inflation,
implantation of a covered stent or embolisation with coils, thrombin or fat to be sealed.
When the perforation results in an extravasation of blood inside the myocardium
(intramural/septal hematoma) or in the sac encasing the heart (pericardial effusion) this
may lead to inability of the heart to properly fill (pericardial tamponade, a complication
which occurs in 0.3-0.9% of cases) and may require pericardiocentesis (puncture under
echocardiographic guidance of the pericardium and insertion of a drainage) or, in
exceptional cases, emergency reparative surgery.
- Periprocedural myocardial infarction (0.6-2.6%), which may be due to: injuries to the
coronary artery from which collateral branches originate (donor vessel
dissection/thrombosis/occlusion) (0.6%), injury to the CTO vessel distal to the occlusion,
side branch occlusion, acute stent thrombosis (0.3%), or air/thrombus/plaque embolisation.
- Aortocoronary dissection (0.8-1.8%): deep engagement of the guide catheter into the
occluded artery or forceful contrast injection at the ostium of the occluded artery may cause
damage to the aortic wall, mostly causing a small haematoma that seals spontaneously over
time but occasionally progressing to an aortic dissection requiring major surgical operation.
- Equipment loss/entrapment (1.5%): most of the times this only cause a prolongation of the
procedure to retrieve it but a permanent loss of a small piece of wire within the occlusion or
distal in the vessel is possible and mainly benign.
- Life-threatening arrhythmias (1.2%): delivery of an external electrical shock (defibrillation)
might be required for malignant tachyarrhythmias or an extra-catheter can be inserted via
the groin to electrically stimulate (pace) the heart in case of bradyarrhythmias.
- Acute heart failure and eventually cardiogenic shock (1.1%): if the use of drugs to support
the heart is not sufficient additional catheters supporting or substituting the action of the
failing heart could be needed. They all require additional catheters inserted from the groin
and include intraortic balloon counterpulsation, a miniaturised pump aspirating blood from
the left ventricle and ejecting it into the ascending aorta called Impella, veno-arterial
extracorporeal circulation (ECMO). In some cases when the risk of heart failure during the
procedure is high before starting, these catheters can be inserted before the procedure.
- Emergency cardiac surgery (0.1-0.7% of cases): this can be induced by the multiple
complications indicated above but it is a very uncommon event.
- Death (0.2-0.9%).
6. Extracardiac complications may include:
- Vascular complications (related to the vessel puncture or closure), such as hematomas,
pseudoaneurysms, arteriovenous fistulas, dissections and occlusions (0.5-1.5%)
- Contrast allergic reactions or contrast-induced nefropathy (0.8-3.8%)
- Neurological complications, such as stroke (<0.01%)
- Skin radiation injury (<0.01%)
- Major bleedings (0.4-0.8%)
Long-term complications that may occur days, months or years after the procedure include stent
thrombosis, a rare event (0-3%) with the use of modern drug eluting stents. To avoid this event, it
is essential that the patient takes the prescribed antiplatelet therapy, often including a combination
of aspirin with a second blood thinning drug. Restenosis is an excessive proliferation of tissue
within the stent that may lead to a recurrence of lumen narrowing (2-8%). When restenosis occurs,
it can be treated with a new angioplasty.
The incidence of these complications depends on the patient's clinical condition (age, severity of
coronary and cardiac disease, the presence of other associated conditions such as diabetes
mellitus), the anatomical characteristics of the occlusion and the type of approach and technique
used. Please discuss with the operator to have more precise rates of success and complications in
your individual case based on the anatomic complexity of the occlusion and the strategy planned
for recanalisation.
7. Alternatives to percutaneous recanalisation
1. Medical therapy, that leaves the patient in the same condition as before, avoiding the
risks of the procedure. Symptoms and impaired exercise capacity, if present, will
remain.
2. Coronary artery bypass surgery, which requires open heart surgery but may be an
alternative in patients with other indications to surgery (i.e., valvular heart diseases) or
in diabetic patients with severe disease of the other coronary arteries in addition to the
occluded one. This option should be discussed on a case-by-case basis with the doctor.
Recovery after a CTO recanalisation
After CTO recanalisation, bed rest is recommended for a number of hours that varies according to
the type of vascular access used (radial or femoral) and should be evaluated on a case-by-case
basis. Radial access allows a faster mobilisation while with femoral access a bed rest of 6-12 hours
is often necessary to achieve effective haemostasis. In any case, once mobilisation is achieved, all
daily life activities can be resumed, always adhering to the indications that will be given at the
time of discharge. Discharge from hospital is often performed the day after a CTO recanalisation.
In the unfortunate event of complications, the hospitalisation will be prolonged according to its
type and severity.
Patient consent form
I …................. patient’s name ...................................................................................... agree to undergo recanalisation of a coronary chronic total occlusion. I acknowledge that I have read the 3-page information sheet and have discussed the risks and benefits of this procedure with my health care professional. I am aware that it is my right to request further explanations at any time. I am also aware that I may revoke my decisions expressed herein up to the time of procedure. Date ........................................... Patient's signature ……………………………………………….……………. Signature of a Family Member (if the patient is unable to provide a consent) ………………………………………………………………………………………………………… …………………………………………. Name and signature of the treating doctor…………….………………………………………………………………….
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