Abstract - University of Kentucky



Is Coronary Artery Bypass Graft Really Better Than Coronary Stents?

(A look at the risks and benefits of both)

Sarah Smith

February 29, 2007

PAS 646

Advisor: Dr. Grimes

ABSTRACT:

Coronary heart disease is the leading cause of death in the United States for both men and women. Coronary artery disease approximately accounts for 43% of these deaths, and by 2020 it will become the world’s most prevalent cause of death and disability. There are multiple treatment procedures that are used to relieve the symptoms and provide a route for blood to flow unobstructed. Coronary artery bypass surgery (CABG) and percutaneous coronary intervention (PCI) with stents are the procedures that are focused in this review. The purpose of this paper is to review current literature, in affect to analyze the benefits and risks of coronary artery bypass surgery and percutaneous intervention with the use of bare-metal stents and drug-eluting stents. Current studies have confirmed that CABG is still the best technique for patients that have proximal left anterior descending, multivessel, and left-main stem coronary artery disease. CABG has also shown that its effectiveness is magnified in patients who are diabetic. PCI has undergone tremendous growth over the past decades with the numerous technological advances. It has evolved from its initial use of balloon angioplasty techniques to use of bare-metal stents and, more recently, drug-eluting stents. PCI with stents was found to be effective in patients that have single-vessel coronary disease, because of its lower clinical risk and reduces angina and myocardial ischemia in patients. The ratio of PCI to CABG use exceeds 4:1. This review analyzes the limitations of both procedures and analyzes the most appropriate procedure for certain types of vessel disease.

INTRODUCTION:

The leading cause of death in the United States is coronary heart disease (Mercado, 2005). Approximately 43% of coronary heart disease deaths are related to coronary artery disease (Mercado, 2005). Coronary artery disease has become the most important cause of death and disability particularly in developed world; approximately 60% of them have multivessel coronary disease that is usually treated with either percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) surgery (Mercado, 2005). There has been a large controversy over the preferred method of treatment of multivessel disease. Many studies and clinical trials have suggested higher restenosis and repeat revascularization rates in patients who were treated with bare metal stents rather than those with surgery. There have been great advances in techniques and devices used including the advancement of drug-eluting stents. Drug-eluting stents have been shown to be much more successful with lower repeat revascularization rates, suggesting that PCI with drug-eluting stents should be considered for the preferred strategy. CABG surgery has been the main surgery used for many years to treat coronary artery disease. I would like to compare the outcomes of both techniques and explore the benefits and risks associated with them. Heart disease is something that affects almost every family and both of these techniques are relatively common and most of the students have probably heard of them or had a family member that has had to go through one of these surgeries. I found this topic interesting because I think the heart and cardiac system is fascinating. Prior to entering PA school I shadowed a PA in multiple CABG surgeries. I thought that this surgery was amazing and wanted to get a little more information about the disease and the techniques commonly used in hospitals. I would like to find out if there is an increased prevalence of repeat revascularization in one or both of these. I would also like to find out the mortality rates after the procedures. I think that CABG surgery has a higher mortality rate during surgery, but possibly a better outcome long-term. I also think that in the patients who receive a stent they will have a higher incidence of repeat revascularization that with CABG. I think that this topic will be very interesting and will hopefully spark some interest in my fellow classmates.

EPIDEMIOLOGY and PATHOPHYSIOLOGY:

Coronary artery disease (CAD) occurs when atherosclerotic plaque builds up in the wall of the arteries that supply the heart. Basically, CAD is a disease caused by “hardening” of the coronary arteries on the surface of the heart (Michaels, 2002). After decades of progression, some of these atheromatous plaques may rupture and start limiting blood flow to the heart muscle. This disease is the most common cause of sudden death and is also the most common reason for death of men and women over the age of 20 years of age. Most recent 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 women (Michaels, 2002).

CAD is a chronic process that begins in adolescence and will progress slowly throughout life. Risk factors include family history of premature CAD, smoking, diabetes mellitus, hypertension, hyperlipidemia, a sedentary lifestyle, and obesity. These risk factors accelerate or modify the process that produces atherosclerotic plaques.

Atherosclerosis is the most common cause of CAD, and plaque rupture is the most frequent cause of myocardial infarction and sudden cardiac death. Atherosclerosis can affect one or all three of the major coronary arteries and their branches, but most commonly in the left anterior descending and left circumflex or right coronary artery.

The first step in the atherosclerotic process is the development of fatty streaks. These streaks form between the endothelium and the internal elastic lamnia (Libby, 2005). Overtime a fibrous cap forms and will play a critical role in the development of acute coronary syndromes. Fixed or stable plaque obstructs blood flow. Stable plaques develop over several decades until they may cause stenosis or occlusion. Unstable or vulnerable plaque can rupture and cause platelet adhesion and thrombus formation.

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 arteries. Over a long period of time, these streaks or atherosclerotic plaques will increase in thickness and may affect the flow of blood through the arteries. As the plaques continue 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 that the patient’s heart is experiencing an increased workload and means that there is reduced blood supply to the heart.

Ischemia means that the supplied oxygen to the tissue is not enough, thus impairs the function of the heart. When large areas become ischemic there can impairment in the contraction and relaxation of the heart. If the blood flow is improved then myocardial ischemia can be reversed, which is unlike an infarction. Infarction means that the tissue has undergone irreversible death of tissue due to lack of oxygen-rich blood. The first symptoms typically seen are angina or decreased exercise tolerance. As the degree of obstruction progresses there can be complete obstruction of the coronary artery, severely restricting the amount of oxygen transported to the myocardium.

Patients present with stable angina, unstable angina pectoris, or a myocardial infarction, acute coronary symptoms. Patients may seek first medical treatment when they experience chest discomfort. The diagnostic approach should include a detailed patient history, a complete physical exam, and an electrocardiogram. It is important to evaluate the patient’s blood pressure and ankle-brachial index and screening for hyperlipidemia and diabetes mellitus. During cardiac auscultation murmurs may be detected due to aortic stenosis or hypertrophic cardiomyopathy. Electrocardiographic results are normal in about 50% of patients with chronic stable angina, therefore a normal EKG does not exclude coronary artery disease (Michaels, 2002). Some things to look for on the EKG are presence of left ventricular hypertrophy, ST-segment changes, T-wave changes, and conduction abnormalities such as left bundle branch block. The appearance of diagnostic Q waves in two continuous leads greatly increases the probability of CAD (Libby, 2005).

Coronary angiogram is currently the golden standard for determining the presence of obstructive coronary artery disease. This procedure yields a two-dimensional picture of the coronary arteries. A catheter is inserted into the coronary arteries and the injection of a dye allows a physician to pinpoint the number and location of blockages in the coronary arteries. After the physician performs this there are many different treatment options that may be taken, including possibly PCI with stent placement or bypass surgery.

Here are some key definitions that are used through out this paper and helpful in understanding the disease. A single-vessel disease is defined as the presence of greater than 50% diameter lumen narrowing in the LAD, left circumflex or right coronary artery, or a major branch of these. Double vessel disease is considered greater than 50% diameter lumen narrowing in 2 of the 3 major branch of any of these. Triple-vessel disease is found in all 3 vessels. Left main disease is the presence of greater than 50% diameter lumen narrowing in the left main coronary artery.

Overview of PCI with stents:

Roughly one-third of patients with CAD will undergo coronary angioplasty with stenting (Michaels, 2001). PCI is also known as coronary angioplasty is used to open clogged heart arteries. Angioplasty involves temporarily inserting and expanding a tiny balloon at the site of the blockage to help widen the narrowed artery. This is usually combined with implantation of stent in the clogged artery to help prop it open and decrease the chance of it narrowing again or restenosis. PCIs are performed in the cardiac catheterization lab and are a non-surgical treatment. This procedure usually lasts about one to two hours and most patients are usually discharged in one or two days after a successful procedure. Stents are a stainless steel or nytinol mesh like device that are placed into the coronary artery on a catheter during the procedure.

Overview of Coronary Artery Bypass Grafting

In recent studies coronary artery bypass grafting (CABG) is still the best therapy for reintervention for most patients with proximal left anterior descending, multivessel, and left main-stem coronary artery disease, in terms of improved survival (Taggart, 2007). Of the patients with CAD, about 10% will undergo CABG surgery (Michaels, 2001). 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. The most common vessels used are the saphenous vein and the internal thoracic artery. Typically this procedure is performed with assistance of a heart-lung machine, which supports the patient’s blood while the surgeon operates on the heart. Minimally invasive bypass surgery is a less traumatic form that relies on smaller incisions to gain access to the chest cavity. This is a navel procedure with not many clinical trials or evidence of its effectiveness.

REVIEW OF LITERATURE:

Comparative Effectiveness of PCI and CABG

The two procedures that are generally used as treatment options for blocked coronary arties are PCI with stents and CABG surgery. A physician will look into the patients’ individual risk factors, severity of the blocked artery, and analyze the benefits and risks of both procedures. These two procedures are different in their techniques and indications. PCI has been proven to have shorter procedural and recovery time with not many adverse affects after the procedure. The main limitation is the incidence of restenosis and the need for revascularization. CABG surgery has shown many benefits such as decrease in angina, improved life-span, and providing an effective route for blood with prevention of new plaques to form. Surgery is however a much more serious operation that lasts a long time and has a longer recovery time. Some complications that are seen after surgery include atrial fibrillation, increased risk of stroke, and cognitive dysfunction.

In 2005, 261,000 CABG procedures and 645,000 PCI procedures were performed in the United States alone (Bravata, 2007). In patients with left main or triple-vessel coronary artery disease, CABG has been the preferred method because it improves survival. In patients with most forms of single-vessel disease, PCI has been shown to be the preferred form of coronary revascularization. The risk of emergency referral for CABG and the need for subsequent revascularization procedures has reduced by more than 50% because of coronary stents (Villareal, 2002). Coronary restenosis has been considered the main limitation hampering the usefulness of percutaneous revascularization. Stent implantation has been shown to reduce restenosis in vessels with reference diameter >3.0 mm, however in-stent restenosis still occurs in about 10-40% of patients (Lemos, 2007). According to the 2005 guidelines issued by the American Heart Association and American College of Cardiology, stents can be considered for use in patients who have significant disease of left main and left anterior descending coronary arteries. Also, stents should be three or two-vessel diseases are also possible candidates. In previous years these patients were only candidates for bypass graft surgery.

In an interesting study (Bravata, 2007), compared the long-term outcomes of both procedures. The study found that procedural survival was high for both procedures: 98.9% for PCI and 98.2% for CABG. Angina relief was more common after CABG than with PCI at 1, 3, and 5 years after the procedure. Patients who received PCI didn’t have angina 75% of the time compared to patients receiving CABG 84% of the time. This study also discovered that there was a great proportion of patients who underwent CABG surgery were without repeated coronary revascularization (96.2% at 1 year and 90.2% at 5 years) compared with PCI (73.5% at 1 year and 53.9% at 5 years).

In another study (Mercado, 2005), patients who received PCI with stents had a significantly lower incidence of death, MI, or stroke at 30-day follow-up to CABG surgery. However, patients receiving stents had a higher incidence of repeat revascularization procedures at 30 days. At a 1-year follow up the incidence of death, MI, or stroke where similar between the two procedures; 8.7% after stents and 9.1% after CABG surgery.

This study supports the main limitation of bare-metal stents that most other studies have found as well, that there is an increased rate of restenosis among patients who receive stents. The main complication of untreated restenosis is refractory angina pectoris (Lemos, 2003). The anticipated high risk of in-stent restenosis is one of the major reasons for patients refusing angioplasty and opting for other treatment modalities. The introduction of drug-eluting stents may hopefully shift patients from surgical procedures toward PCI. Long-term follow-up in patients with bare metal stents shows that tissue proliferation reaches its peak at around 6-12 months and then regresses (Daeman, 2007).

In recent years, drug-eluting stents have become a pharmacologic advance that has aided in the reduction of re-stenosis which happens with the bare-metal stents. These stents are a normal metal stent that has been coated with a drug that is known to interfere with the process of restenosis. As of December 2007, the FDA has approved two drug-eluting stents: sirolimus-eluting stents and paclitaxel-eluting stents.

In a recent study (Kaiser, 2005), it states that there is an overall 44% reduction rate of major adverse cardiac events with drug-eluting stents compared with bare-metal stents. This study suggests that possibly drug-eluting stents could be restricted to certain high-risk patients subgroups such as high-risk elderly patients with three-vessel disease, treatment of multiple segments.

There are a couple of problems with the drug-eluting stents however. One problem is that the agents loaded on the stents can interfere with the healing process. On detailed examination of the area where stent was introduced there was adhered platelets and inflammatory cells, and absent endothelium for prolonged periords ( Morton, 2007). Second, in a study (Daemen, 2007), found the drug-eluting stents proved to hamper the natural vascular healing process. Third, the drug-eluting stents are still being debated as to their cost-effectiveness.

Even higher rates of reduced rates of restenosis by 70%-90% compared with conventional bare-metal stents in a recent study (Ryan, 2006). The drug-eluting stent were first introduced in April, 2003, and just 9 months later they made up 35% of all stent implantation in the United States (Ryan, 2006). This study also analyzed the cost-effectiveness of drug-eluting stents. It was determined that many US centers pay roughly $2200 per drug-eluting stent, when compared with an average $600 per bare metal stent. Since most procedures require more than one stent, the price per procedure is actually an increase of $2500. This higher upfront increase may offset the reduced repeat revascularization procedures. This study determined that there was still an increase of

$600 per PCI patient, and with an estimate of 1 million PCI procedures per year that is about $600 million in increased annual healthcare spending. This increase in cost on the health care system could cause a dilemma on the economic perspective of the US healthcare system and in this study it is suggested that drug-eluting stents might bankrupt the system

Another study also analyzed the cost effectiveness of drug-eluting stents, since the stents are much more expensive than bare metal stents (Kaiser, 2005). In a study (Lemos, 2003), suggested that there is a potential $2000 difference between drug-eluting stents and bare stents, which if every person that went under PCI received a drug-eluted stent would be an extra $2.4 billion difference in costs per year. Drug-eluting stents reduce the risk of restenosis in low-risk coronary lesions, but do not reduce the risk of mortality or subsequent myocardial infarction. In an interesting study (Farb, 2007), suggested that stent thrombosis appears to be potentially important limitation of drug-eluting stents associated with an increased risk of myocardial infarction of 65-70% and of mortality of 25-45%. While the precise incidence of stent thrombosis with drug-eluting stents is unknown, the FDA has cautioned that the use of drug-eluting stents is associated with increased risks of both early and late stent thrombosis, as well as death and myocardial infarction (Farb, 2007). It will be interesting to see the continued clinical trials on drug-eluting stents to see how effective they are and what future indications they could be used for.

Implantation of bare metal stents have showed to be effective for single vessel disease, however there are limitations First, stents cause permanent physical irritation with the risk of long-term endothelial dysfunction or inflammation (Virmani, 1999). Second, stents pose a high thrombogenicity (Tepe, 2002). Third, stents create an inability for the vessel to remodel and act in a normal physiological way (Hofma, 2006). Fourth, stents create difficulties for possible future bypass surgery and noninvasive imaging. Finally, probably the biggest limitation is revascularization with bare metal stents, as mentioned prior.

CABG surgery was introduced approximately 50 years ago and is now performed in 1 million patients at a cost exceeding $20 billion annually (Ott, 2007). The long term results of CABG surgery are generally positive and include relief of symptoms of angina, improvement in energy levels after recovery, and improved expected life-span for specific subgroups of patients. Angina relief is more common after CABG than after PCI. At a 1 year proportion of patients without angina was 75% in PCI patients compared with 84% in patients who underwent CABG surgery. CABG is superior to PCI in mutivessel CAD in terms of death, myocardial infarction, and repeat revascularization regardless of stent type (Yang, 2007). CABG is the preferred treatment for disease of left main coronary artery and three-vessel disease. CABG is generally the preferred treatment with other high-risk patients such as those with sever ventricular dysfunction or diabetes mellitus.

Some limitations of bypass surgery have been discovered. Bypass surgery carries some risks, including a less than 5% chance of heart damage and less than 2% chance of death (Stephenson, 2004). Cognitive dysfunction is reported in 53% of CABG surgery patients at discharge, 36% at six weeks, and 42% at five years (Harmon, 2004). It has also been found that stroke or neurological injury occurs in 5% of patients undergoing CABG surgery (Medline Plus). Blood platelet transfusions during CABG surgery have been association with a three-fold increased risk of stroke and five-fold increased risk of death (Spiess, 2004). Some other complications associated with CABG surgery include bleeding, infection, difficulty breathing, hypertension, abnormal heart rhythm; particularly atrial fibrillation. All of these risks are higher for older patients, diabetics, patients with other major health problems and those undergoing a repeat bypass procedure (Stephenson, 2004)

Atrial fibrillation occurs in 20%-40% of patients after CABG (Zaman, 2000). One study (Zaman, 2000) discovered that 28.2% of the patients developed atrial fibrillation. They discovered a couple of risk factors that might contribute to this risk factor associated with CABG surgery. Advanced age was strongly associated with postoperative atrial fibrillation. The mean age in this study was 65.9 in the atrial fibrillation group compared with 61.7 years in the non-atrial fibrillation group. There was an increased incidence of atrial fibrillation in patients aged 70-74, 42.2% chance of developing atrial fibrillation. It is important for a patient and their doctor to look into their risk factors and helping to identify the vulnerable patients for atrial fibrillation.

There are two reasons as to why CABG offers survival advantages for multivessel and left main-stem coronary artery disease. First, since bypass grafts are placed on the midcoronary vessel, CABG does not only protect whole zones of vulnerable proximal myocardium against the culprit lesion, but it also offers prophylaxis against new lesions in diseased endothelium (Taggart, 2007). PCI in contrast, only treats the immediate culprit lesion, but has no protective effect against the development of new proximal disease. Second, the failure of stenting to achieve complete revascularization in most patients with multivessel disease reduces survival proportional to the degree of incomplete revascularization (Taggart, 2007).

Isolated LAD and Left main-stem coronary artery disease

Coronary artery disease involving the left anterior descending artery (LAD) incidence has been reported as high as 50% among patients who undergo CABG (Aziz, 2007). The LAD coronary artery supplies the vast majority of the myocardium. LAD artery arises off a branch of the left coronary artery. The left anterior descending artery usually follows the anterior interventricular groove and in some people continues over the apex. This artery supplies the anterior septum and anterior wall of the left ventricle. It has been discovered that patients with significant LAD disease, particularly when the proximal part is affected, have adverse prognosis compared with patients who do not have LAD involved (Okeefe, 1999). CABG is regarded as an accepted golden standard for left main coronary artery disease (Gupta, 2007).

There are numerous articles that suggest similar results as stated above. In a meta-analysis (Rao, 2007), it was found that initially PCI with stents are cheaper and more effective than bypass surgery, but surgery is more cost effective long term. It was found that the overall cost for stenting was $12508 per patient and bypass cost about $14459 per patient. In this same study it demonstrated that an internal mammary artery graft to the LAD artery by a minimally invasive approach is both clinically and economically more effective than stenting with bare metal stents over a 4-year period. PCI resulted in a three-fold increase (13%) in recurrent angina and the need for reintervention in comparison with surgery (4%) (Aziz, 2007).

In another study (O’Keefe, 1999), it was discovered that using stent or CABG resulted in low in-hospital morbidity and mortality rates and good immediate-term results. They also discovered that with stents repeat revascularization was required significantly more often (O’Keefe, 1999). In patients that received stents at a 6-month follow-up had superior exercise tolerance and improved anginal status, but is limited to frequency of restenosis. In the patients that underwent CABG the mean length of stay was 5 days after surgery, versus only 1 day for stent patients.

Patients with isolated left main coronary artery disease should be considered for CABG. Left-main stem stenosis is reported to be present in 4-6% of patients undergoing coronary angiography (Taggart, 2007). 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.

In a recent study (Serruys, 2005), it was discovered that the restenosis rates were 30.3% in bare-metal stent group, 7.4% in drug-eluting stent group, and 3.7% in CABG group. It was argued that the drug-eluting stent group might save the patients from fear and pain of surgery while giving equal benefits of survival and reduced rates of restenosis and need for repeat revascularization. Another study (Lee, 2006), suggested that PCI with drug-eluting stents can be considered reasonable if revascularization is essential to save the life and to improve the cardiovascular outcome in patient who is not suitable for CABG.

PCI should be considered as an alternative to CABG under the following circumstances. First, in a patient who refuses CABG surgery. Second, in a patient that is considered unsuitable for CABG by cardiac surgeon in view of co-morbidities or complications. Finally, should be considered if the lesion location where stenting can be done safely (Gupta, 2007).

Multivessel Coronary Artery Disease

Multivessel coronary disease (MVD) accounts for approximately 60% of the CAD patients (Yang, 2007). There are numerous studies comparing the two methods for treatment of the MVD. Numerous studies have reported that the use of stented patients has resulted in higher restenosis and repeat revascularization rates than in patients treated with surgery. In one study (Serruys, 2001), patients that underwent stenting, 16.8% compared with 3.5% that underwent surgery encountered repeated revascularization. This study also found that there was greater angina relief with surgery than with stents after one year. They did not find a significant difference between the rate of death, stroke, and myocardial infarction. The use of stents however is less expensive than surgery. The total cost of bypass surgery was estimated at $10,653 as compared to stenting at $6,441. The difference in cost is primarily due to the length of stay in the hospital and the duration of the procedure.

In an interesting study (Bair, 2005) that followed the long-term outcomes between the two identified a significant difference. This observational study of patients with MVD, followed patients for more than 5 years of follow-up discovered that CABG was found to have a significant survival advantage over patients undergoing PCI with stents. The CABG patients also experienced fewer repeat revascularization and MI and 43% fewer events for the composite end point of major adverse cardiovascular events.

The development of drug-eluting stents has decreased the difference between CABG and bare-metal stents. As mentioned earlier drug-eluting stents reduce the restenosis percentage and thus many clinical trials have been conducted in order to consider PCI with drug-eluting stents as the treatment for MVD. In one study (Yang, 2007), there was significantly higher in-hospital morbidity associated with bypass surgery (3.9% vs. 0.8%). There were similar percentages in the incidence of death, myocardial infarction, and cerebrovascular events in the two groups. Finally, the incidence of major adverse cardiovascular events was still higher in the PCI group in the long-term follow-up (14.5% vs. 7.9%). This difference was mainly driven by the repeat revascularization after PCI.

In another study (Javaid, 2007) similar results found CABG resulted in improved major adverse cardiovascular and cerebrovascular event in patients with 2 and 3 vessel disease. In order for PCI to replace CABG as the preferred therapy in MVD clinical trials must demonstrate that long-term outcomes are at least equivalent. There are currently a couple of clinical trials studying the long-term effects of drug-eluting stents and CABG, but have not finished yet.

The Diabetic Patient

The diabetic patient is at a high risk for coronary artery disease. The incidence, as well as severity of the disease, has been shown to be highly increased in comparison to the nondiabetic patient (Elsasser, 2006). These patients are at an increased rate for short- and long-term mortality as well as higher risk of revascularization procedures. The revascularization of these patients has been a huge dilemma and a great challenge. A study (BARI Investigators, 2007), confirmed that even in relatively low-risk diabetic patients there is a survival advantage at 10 years for CABG in comparison with PCI of 58% vs. 46%. This study also concluded that there was a large difference in the need for reintervention in both of these; 18% of CABG patients versus 80% of PCI patients. These results are also consistent with a 5-year survival data finding that CABG was 92% survival vs. 87% for PCI (Serruys, 2005). This study also found that the need for reintervention was much higher with PCI than with CABG; 10% of CABG patient and 43% of PCI patients.

Another study suggests that CABG surgery may be the preferred revascularization strategy in the diabetic patient with MVD. In the study (Javaid, 2007) the incidence of MI was similar between the two groups of patients. The patients who underwent CABG showed reduced mortality; 1.4% for CABG patients and 12.8% for PCI patients. Also, this showed a reduced rate of major adverse cardiovascular events; 8.6% for CABG patients and 26.6% for PCI patients. These results support the theory that in the diabetic patient CABG surgery benefits are magnified when compared to PCI and possibly is the preferred method for these difficult patients

The Future

In recent years, minimally invasive direct coronary artery bypass (MIDCAB) has been used for treating patients with proximal stenosis of LAD (Jaffery, 2007). 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. This procedure enables a shorter hospital stay with lower postoperative complications and better quality of life with similar safety and long-term efficacy as conventional CABG (Jaffery, 2007). There are a couple of studies that are compared to PCI. In a study (Aziz, 2007) PCI resulted in a three-fold increase in recurrent angina and the need for reintervention than with MIDCAB. This new technique has only started to take some ground in the strategy for treating CAD, it will be interesting to see what future clinical trials come out and what finding may be made. Maybe this new technique will help propel surgery back into the treatment of not only MVD and LAD artery disease.

A minimally invasive surgery also has developed into the use of wrist-enhanced robotic instrumentation. It is leading to a turning point in the history of MICS (Kappert, 2006). The first patient to receive robotically-assisted coronary artery bypass surgery was in 2002. This surgery does not have a single chest incision of any kind. This surgery requires only three pencil-sized holes made between the ribs. Through these holes, two robotic arms and an endoscope gain access to the heart, making surgery possible without opening the chest. It has been proven that these patients get out of the hospital one to two days earlier than open-heart surgery. There are several centers that are currently using surgical robots and the use of them is still in its youth and studies still need to be done to understand it better. This technique might as well be a new technology that might be used more often in the future and maybe even replace bypass surgery.

CONCLUSION:

Current studies have reconfirmed that CABG remains the best therapy in terms of superior survival and decreased need for reintervention for most patients with proximal left anterior descending, multivessel, and left main-stem coronary artery disease. These affects are magnified in the diabetic patients. PCI is still chosen as the treatment option for single-vessel disease. Coronary stents treat diseased arteries with fewer trauma on the patient than with bypass surgery. Stents have proven to reduce chest pain, lower risk of heart attack after the procedure, and decreased hospital and procedural time. The only limitation that has been a problem is restenosis of the artery and the need for revascularization.

As technology continues to advance, stents are becoming superiof for patients with more complex disease, therefore reducing the number of surgeries. With the evolution of drug-eluting stents and minimally invasive surgeries with assist of robots the current guidelines may change. It will be interesting to see where revascularization will be in the next five years.

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