MISSOURI STATE UNIVERSITY
Fall 2010
An overview of PCI vs CABG for Severe Coronary Artery Disease
Luis Hernandez
Physician Assistant Studies
PAS 797
Abstract
Introduction. For many years more sophisticated invasive procedures have been
developed to stop the life threatening complications of coronary artery disease. Currently,
drug-eluting stents (DES) represent a real option for many patients with severe acute
coronary syndromes, which create a clear challenge for the former goal standard coronary
artery bypass grafting. This review provides a synopsis of the outcomes of recent studies.
Methods. A specific criterion was chosen to select online peer-reviewed articles that
compared both procedures for severe coronary artery disease. At the same time, online
textbooks were reviewed for the background of this study.
Discussion. Even though DES have decreased the number of early revascularization
when that is compared with bare-metal stents, some studies still show significant
complications from the new technique. On the other hand, the outcomes of CABG vary
from one study to another.
Conclusion. Patients need to be evaluated individually before determining which
procedure gives the patient a safer or more convenient path. Many factors are involved
and each one is required to be analyzed.
Before the 20th century, infections and malnutrition were the main causes of death
around the world. However, a better public health system, industrialization, and lifestyle
changes have shifted the numbers. Now, cardiovascular disease is the number one cause,
which counts for around 30% of deaths worldwide. The good news is that coronary artery
disease has decreased by 75% in the United States in the last 40 years; nevertheless,
cardiovascular disease (CVD) is responsible for 40% of all deaths, which represents
around 1 million deaths per year 1. At the same time, it is known that 1.5 million visits US
emergency rooms are related to acute coronary syndromes (ACS). Patients with ACS
normally have a rupture of an atherosclerotic plaque, associated with a significant
thrombosis in the coronary arteries. As a result, 21% presents with STEMI (ST-elevation
myocardial infarction), 36% with non-STEMI, and 43% with unstable angina. These
astronomic numbers have generated improved treatment outcomes for ACS in the last
decade. As a result, experts have developed guidelines for specific coronary events like
the one created by the American College of Cardiology/American Heart Association in
2007 for patients with unstable angina/non-STEMI, which represents the most recent
recommendations for this group of patients who are at high risk of death or MI (figure 1
depicts the most recent guideline). These patients have repeated chest pain, abnormal
cardiac enzymes, heart failure, hemodynamic instability, high-risk signs during noninvasive testing, sustained ventricular arrhythmia, or EF less than 40%. The specific
guidelines for them are early coronary angiography and revascularization with
percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) 2.
2
ACC/AHA Guidelines
Fig. 1. Anderson J, Adams C, Antman E, et al. ACC/AHA 2007 Guidelines for the
Management of patients with Unstable Angina/Non-St Elevation Myocardial Infarction. Journal of
the American College of Cardiology. 2007, 50:1-157. Copied without permission.
In the beginning, PCI was done with balloon angioplasty itself, but close to 50%
of patients had restenosis in the next 6 months and ultimately resulting in repeat
angioplasty or open-heart surgery. The creation of bare-metal stents after angioplasty
reduced the cases of restenosis, but many still needed a repeat procedure. With the
creation of drug-eluting stents, which secrete an antiproliferative drug, restenotic events
have decreased in 10% and now 75% of the PCI procedures are done in the United States
with DES. The other main complication of PCI is thrombosis which can occur
immediately, days, or weeks after the procedure. This is caused by deficient
expansion/apposition during the procedure, stopped antiplatelet therapy, or both. Patients
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who have stent placement receive antiplatelet and anticoagulant drugs; aspirin forever,
clopidogrel for a period of time depending on the type of stent, glycoprotein IIB-IIIA
inhibitors (as soon as possible after presentation of the coronary event and 24 hours after
the stent), and intra-procedural heparin 3.
On the other hand, Coronary Artery Bypass Graft uses autologous veins (usually
saphenous) or arteries (internal mammary, radial). The venous bypass is 85% patent in
one year, but arterial bypass is 97% patent in 10 years. MI and stroke are the main
complications of this procedure. However, if the patient has a normal sized heart, no
previous MI, and good ventricular ejection function, the perioperative risk for MI and
stroke is less than 5%; and less than 1% risk of death. Also, some cardiovascular centers
are seeing increasing numbers of off-pump CABG, which minimizes the risk of cognitive
dysfunction seen in 25% of patients after on pump open heart surgery 4.
It is important to mention that before the use of DES, it was evident that CABG
offered several advantages compared with PCI. This included fewer of repeat cases and
better outcomes i.e., chronic occluded coronary arteries. On the other hand, DES are
generating great results and many think that repeat procedures will not be required in the
future. Hence, both procedures have advantages and disadvantages, which produce many
questions when cardiologists and surgeons are trying to decide which one is “the best
procedure” for a patient with CAD. Therefore, this study will review observational and
controlled trial studies that compare the outcomes of both procedures performed in the
last 10 years 5.
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Methods
The method utilized by this research included peer-reviewed journals comparing
CABG versus PCI in patients with severe coronary disease. In addition, database such as
the New England Journal of Medicine, The American College of Cardiology, and The
European Journal of Cardio-Thoracic Surgery were also analyzed. Both online textbooks
and articles from Merckmedicus and Medscape were also used to assemble the
background of this study.
A specific criterion was followed for the selection of articles. Clinical trials that
involved high volume of patients were particularly preferred to bring more statistical
power to this study. As a result, conclusions were generated from a total database of more
than 35,000 patients.
On the other hand, studies that were completed after 2003 were chosen. The
reason was to make sure that not only bare-metal stents were included, but also studies
where DES-PCI procedures were performed; procedure that has been in the market since
2003. At the same time, the studies that included mainly PCI or CABG for patients with
left main coronary artery disease or multi-vessel coronary disease were chosen.
Discussion
It is impossible to evaluate both techniques if the discussion is not based on
results of other studies. Hence, findings of three different studies will be presented in
which PCI and CABG were performed in patients with severe coronary artery disease.
A group of European doctors performed a meta-analytic computerized search of
peer-reviewed-retrospective observational (English only) studies published until 2008
that compared outcomes of DES-PCI vs CABG for patients with multivessel coronary
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disease. Nine observational non-randomized studies were analyzed, which totalized 24,
268 patients with multivessel coronary disease; 13,540 had PCI and 10,728 CABG.
Patients were followed for 20 months (mean) after the procedure (see table 1). There was
not a significant different between both procedures regarding death, acute myocardial
infarction, and cerebrovascular accidents; however, a significant higher risk of repeat
revascularization in patients who underwent DES-PCI. In addition, the results did not
change substantially when comparing diabetic patients and overall population 6. Table 1
reflects data presented by computerized search done by the members of the School of
Medicine in Italy.
Benedetto U, Melina G, Angeloni E, et al. European Journal of Cardio-Thoracic Surgery. 2009. 36:611-615.
Copied without permission
Seung et al. performed an observational study of a total of 2,240 patients with
unprotected left main coronary artery disease (more than 50% stenosis) who had PCI vs
CABG in 12 different major cardiac centers in Korea between 2000 and 2006. Baremetal stents only used between Jan 2000 and May 2003 and DES-PCI only used since
May 2003 through Jun 2006; bypass surgery done using standard techniques. Patients
were followed at 1 month, 6 months, and 1 year; then yearly. Mean follow up for PCI
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group was 1017 days and 1152 days for the CABG group. The end points of the study
were death, MI, stroke, or repeat revascularization. The outcomes of PCI techniques were
compared, individual PCI techniques were compared with CABG, and PCI techniques
(any type) compared with CABG. From the 2240 patients included in the study, 1102
were selected for PCI and 1138 for CABG. From a total of 542 matched pairs, similar
outcomes were seen in both procedures during the 3 –year follow up (death, MI, or stroke
rates). However, the rate of revascularization was significantly higher in the group of
patients who underwent PCI (any type) and also higher risk of revascularization for
mainly restenosis of the left main coronary artery (lower risk in the DES group). Among
the patients not included in the match, the rates of death, MI, or stroke were significantly
higher in the CABG group; but revascularization rates higher in the PCI group 7.
Outcomes from both procedures done in New York for 17,400 patients with
multivessel coronary disease were analyzed in a study that retrieved data since Oct 2003
through Dec 2004, with follow up (mean of 19 months) until Dec 2005. A number of
9963 patients received DES and 7437 patients CABG. The results showed also a higher
rate of revascularization for patients who underwent DES-PCI. In addition, CABG was
associated with lower death or MI rates (with or without LAD involvement) than treated
with DES in patients with two or three-vessel disease 8.
It is evident that revascularization is still a problem for DES, but it is important to
point out that this type of stents has been in the market since 2003 8. Ongoing studies
should be evaluated, which are already showing better numbers for DES- PCI 6.
Nevertheless, two studies have shown patients who have been complicated with
thrombosis after the use of DES, which a meeting at the FDA was required to debate
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about the safety of the device 8. It has been described in the literature that stent
thrombosis could have more serious complications for patients (MI, death) than does
CABG’s occlusion, where angina has been the result and cause of revascularization.
However, lower rates of stroke have been shown among patients who have had PCI,
possibly from an effective use of dual-antiplatelet therapy. The question is if a more
aggressive anti-platelet therapy could bring substantial benefits to patients who undergo
to CABG 9.
On the other hand, these studies and others have a very common problem, the
selectivity of the patients. Many of them are selected for a particular procedure at
discretion of the treating physician and their practice could be different from other
cardiac centers. Moreover, procedures can be selected also by patients, who don’t want to
have an open chest surgery or maybe don’t want to go to the OR more than one time;
therefore, CABG could be a better option for them. Also, it is common to see a short
period of follow up in many studies, where just one to three years have set conclusions
about their findings 7. On the other hand, chronic diseases involved and age of the
patients can be determinant factors to decide which procedure to follow. In some way, it
does not seem realistic to compare both procedures when different factors are involved.
On the other hand, a grading system was created to guide cardiologists and
surgeons when selectivity of the procedure is an issue; the SYNTAX score. The
SYNTAX trial was a randomized study designed to compare both procedures in patients
with left main coronary artery and/or three-vessel disease. The rates of death were similar
for both procedures at one year; however, the rate of repeat revascularization was higher
in the PCI group and rate of stroke higher in the CABG group. This trial also designed a
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SYNTAX score, which was based on anatomical characteristics and extent of lesions.
Hence, a higher score is given to patients with more complex anatomy and higher
functional risk of occlusion. This would create a more difficult scenario, worse prognosis,
and higher risk to do a PCI 9.
Conclusions
While balloon angioplasty techniques have been improved by the use of different
types of stents, a variety of open chest surgical approaches have been developed to avoid
early revascularization and other life threatening complications such as thrombosis and
stroke after DES. However, data from current procedures using DES are not available
yet. Also, different conclusions have been generated from studies that have evaluated
outcomes from only one year, which it does not seem enough time. On the other hand,
2007 guidelines suggest CABG as the goal standard for patients with left ventricular
dysfunction, left main artery disease, or more than two compromised vessels. Even
though guidelines have been established, a variety of outcomes from both procedures still
generate many questions.
This study concludes that many factors need to be evaluated before deciding
which technique is more appropriate for the patient; age, chronic diseases involved
surgical risk, patient decision, or physician preference. There is no doubt that despite
DES being a newer technique, current data suggest long term outcomes will favor its use.
The good news is that even though coronary artery disease is still the number one cause
of death in America, techniques are evolving and unexpected complications are already
decreasing.
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