Is Coronary Artery Bypass Surgery
Really Better than Coronary Stents?
A look at the risks and benefits
Advisor: Dr. Grimes
Why is this important?
The leading cause of death in the United States is
coronary heart disease
It accounts for about 1 million deaths per year
About 43% of heart disease deaths are related to
coronary artery disease
Heart disease is the leading cause of death of
American women, accounting for 32% of all
deaths per year.
One in three women will die from heart disease, while
one in 25 will die from breast cancer
Trends in the United States suggest that half of
healthy 40-year-old males will develop CAD in the
future, and one in three healthy 40-year-old
CAD is a chronic disease in
which the coronary arteries
gradually harden and
Limitation of blood flow to
the heart causes ischemia
of the myocardial cells,
leading to a myocardial
This leads to heart muscle
damage, heart muscle
death and later scarring
without heart muscle
CAD can be thought of as a wide spectrum of
disease of the heart
At one end is the asymptomatic individual with
fatty streaks within the walls of the coronary
Over time these streaks will increase in thickness and
may affect the flow of blood through the arteries
As the plaque continues to grow and obstruct the vessel
to more than 70% the patient typically develops
symptoms of obstructive coronary artery disease
At this stage the patient is said to have ischemic
heart disease, meaning the patient’s heart is
experiencing an increased workload, thus reduced
blood supply to the heart walls
As CAD progresses, there may be nearly
complete obstruction of the lumen of the
Patients at this level have typically suffered
from 1 or more myocardial infarctions, and
may have angina at rest and pulmonary
An individual may develop a rupture of a
plaque at any stage of the spectrum.
The acute rupture a plaque may lead to an
Family history of premature CAD
Generally patients present with stable
angina, unstable angina, or a myocardial
Coronary angiogram is currently golden
standard for determining the presence of
obstructive coronary artery disease
Yields a 2D picture of coronary arteries
A catheter is inserted into the coronary arteries
and injected with dye
The dye allows the physician to pinpoint the
number and location of blockages in the
There are many different treatment options
A physician will look into the patients’
individual risk factors, severity of the
blocked artery, and analyze the benefits
and risks for possible procedures
Two popular procedures are PCTA/stent
implantation and CABG surgery
Medical therapy is also available for a more
Overview of Stents
1/3 of patients with CAD will undergo coronary angioplasty
with stents or Percutaneous Transluminal Coronary
Angioplasty involves temporarily inserting and expanding a
tiny balloon at the site of blockage to help widen the
Usually combined with stent implantation in the artery to
help prop it open and decrease the chance of it narrowing
again or restenosis
Performed in cardiac catheterization lab and are non-surgical
Usually last about 1-2 hours and most patients are usually
discharged in 1-2 days after a procedure
Stents are a stainless or nytinol mesh like device
Angioplasty and Stents
A stent is a stainless tube with slots. It
is mounted on a balloon catheter in a
collapsed state. When the balloon is
imflated, the stent expands and pushes
itself against the inner wall of the
The risk of emergency referral for
CABG and need for subsequent
revascularization procedures has
reduced by more than 50% because of
Stent implantation has shown to
reduce restenosis in vessels with
reference diameter >3mm, however
in-stent restenosis still occurs in about
10-40% of patients
According to the American Heart
Association stents can be considered
for use in patients who have significant
disease of left main and left anterior
descending coronary artery. Also
patients with 2 or 3-vessel disease
should be considered
In previous years these patients
were only candidates for bypass
Risks/Benefits of Stents
Benefits: Risks and Limitations:
Shorter procedural and Risk of death <1%
recovery time than Risk of heart attack,
CABG thrombosis and
Angina relief about bleeding <4%
75% of the time Major limitation of
Decreases the risk for procedure is a high rate
heart attack of restenosis and need
Increases blood flow to for revascularization
the heart Scar tissue formation
Not a cure to the
disease, still need to
reduce risk factors and
make lifestyle changes
to prevent future
Patients receiving stents had lower incidence of
death, MI, and stroke at 30-day follow-up
compared to CABG.
However, patients receiving stents had a higher
incidence of repeat revascularization procedures
25% of patients at 1 year and 47% at 5 years
This high risk of restenosis is one of the major
reasons for patients refusing angioplasty and
opting for other treatment modalities like surgery
The introduction of drug-eluting stents may shift
patients from surgical procedures back to
angioplasty and stent use.
These are stents that are coated with a
drug that is known to interfere with the
process of restenosis
As of December 2007, the FDA has
approved of 2 DES: sirolimus-eluting stents
and paclitaxel-eluting stents
Studies show that there is a 70-90%
reduced rate of restenosis when compared
with bare-metal stents
DES were first introduced in April 2003,
and just 9 months later made up 35% of
all stent implantations in the United States
Problem with DES?
1. They are expensive
It costs about $2200 for a DES, when compared to bare-metal
stents which costs about $600.
In one study they looked at the cost-effectiveness of DES.
They took into account the fact that there will be reduced
repeat revascularization procedures, and discovered that there
was still an increase in $600 per patient, and with an estimated
1 million procedures done a year, about $600 million increased
in annual healthcare spending
2. The drug agents can interfere with the healing process
and found to hamper natural vascular healing process
In 2007, the FDA has cautioned the use of DES, because they
are associated with increased risks of both early and late stent
thrombosis, as well as death, and myocardial infarction
DES are still a novel idea; it will be interesting to see the
research that comes out in the next couple years looking at
their effectiveness and future indications
Overview of CABG
CABG is still the best therapy for
reintervation for most patients with
proximal left anterior descending,
multivessel, and left main-stem
coronary artery disease
Of the patients with CAD, about 10%
will undergo CABG surgery
CABG is a surgery that increases blood
flow to the heart by creating a detour
and re-routing the blood flow around
the blocked portion of the artery.
A section of a blood vessel from
another part of the body is removed
and grafted above and below the
damaged portion of the coronary
artery to form an un-blocked artery
Most commonly used are the
saphenous vein and internal thoracic
This procedure is performed with
assistance of a heart-lung machine,
which supports the patient’s blood
Risks/Benefits CABG surgery
CABG was introduced about 50 years ago and is
now performed in 1 million patients at a cost
exceeding $20 billion annually
Many benefits such as decrease in angina,
improved life-span, and providing an effective
route for blood with prevention of new plaques to
Surgery is however a much more serious operation
that lasts a long time, with a long recovery time
Some complications seen after surgery are atrial
fibrillation, increased risk of stroke, and cognitive
Less than 5% chance of heart damage and less than 2%
chance of death
Stroke or other neurological injury occurs in 5% patients
Atrial fibrillation occurs in 20-40% of patients after CABG
2 reasons as to why CABG offers survival advantages for
multivessel and left main-stem coronary artery disease
1. Bypass grafts are placed on the midcoronary vessel, CABG
not only protects the culprit lesion, but also offers prophylaxis
against new lesions in diseased endothelium
Where stents only treat immediate culprit lesion, with no protective
effect against the development of new disease
2. failure of stents to achieve complete revascularization in
most patients with multivessel disease reduces survival
proportional to the degree of incomplete revascularization
Isolated LAD and Left-main
CAD in LAD has been reported as high as 50%
among patients who undergo CABG
CABG is regarded as an accepted golden standard
for left main coronary artery disease
CABG has generally been considered the golden
standard of therapy for left-main stem stenosis for
the last decade.
However, there are recent studies out that show patients
underwent PCI more than CABG for this type of disease.
This artery has a relatively large diameter, making it an
attractive site for PCI
Restenosis rates in a study were 30.3% in bare-metal
stents, 7.4% in DES group, and 3.7% in CABG group
MVD accounts for approximately 60% of the CAD
The use of stents in these patients has resulted in
higher restenosis and repeat vascularization rates
than in patients treated with surgery
Stents group had 16.8% restenosis rate as compared
with 3.5% who underwent surgery
CABG patients also experience fewer MI and major
adverse cardiovascular events
DES have decreased the difference between CABG
and bare-metal stents
In order for PCI to replace CABG as the preferred
therapy in MVD, clinical trials must demonstrate
long-term outcomes that are equivalent
What about the Diabetic
The diabetic patient is a high risk for coronary artery
disease, the incidence and severity of the disease are higher
as compared to nondiabetic patient
Revascularization of diabetic patients has been a huge
dilemma and a great challenge
A study confirmed that even a low-risk diabetic patient there
is a survival advantage at 10 years for CABG in comparision
with PCI of 58% vs. 46%
Also found that there is a huge difference in the need for
revascularization in both; 18% of CABG patients and 80% of
Studies state that the preferred revascularization strategy in
the diabetic patient with MVD is CABG surgery
Lower mortality in CABG patients vs. PCI patients (1.4% vs.
Lower major adverse cardiovascular events (8.6% vs. 26.6%)
Minimally invasive direct coronary artery bypass (MIDCAB) is
on the rise
It is performed on a beating heart with use of stabilizing
devices or using minimal access bypass system with endo-
aortic clamping and cardioplegic arrest
Yields shorter hospital stay with lower postoperative
complications and better quality of life with similar safety
and long-term efficacy as conventional CABG
Robotic instrumentation is also developing
Surgery does not have a single chest incision of any kind, this
surgery requires 3 pencil-sizes holes made between the ribs
2 robotic arms and an endoscope gain access to the heart,
making surgery possible without opening the chest
Has been proven that these patients get out of the hospital 1-2
This technique may develop into new technology that might be
used more often in the future and may replace open heart
CABG still remains that best therapy in terms of
superior survival and decreased need for
reintervention for most patients with proximal
LAD, multivessel, and left main-stem CAD.
These affects are magnified in the diabetic patient
PCI with stent is still chosen as treatment option
for single-vessel disease, and now considered for
2 or 3-vessel disease
Each patient is evaluated for the best treatment
option based on their own risk factors and
progression of disease
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