Risks and benefits of coronary stenting vs. CABGPresentation Transcript
Is Coronary Artery Bypass Surgery Really Better than Coronary Stents? A look at the risks and benefits Sarah Smith 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 women
CAD is a chronic disease in which the coronary arteries gradually harden and narrow
Limitation of blood flow to the heart causes ischemia of the myocardial cells, leading to a myocardial infarction
This leads to heart muscle damage, heart muscle death and later scarring without heart muscle regrowth
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 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 coronary artery
Patients at this level have typically suffered from 1 or more myocardial infarctions, and may have angina at rest and pulmonary edema
An individual may develop a rupture of a plaque at any stage of the spectrum.
The acute rupture a plaque may lead to an acute MI
Family history of premature CAD
Generally patients present with stable angina, unstable angina, or a myocardial infarction
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 coronary arteries
There are many different treatment options available
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 conservative treatment
Overview of Stents
1/3 of patients with CAD will undergo coronary angioplasty with stents or Percutaneous Transluminal Coronary Angioplasty (PCTA)
Angioplasty involves temporarily inserting and expanding a tiny balloon at the site of blockage to help widen the narrowed artery
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 treatment
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 coronary artery.
The risk of emergency referral for CABG and need for subsequent revascularization procedures has reduced by more than 50% because of coronary stents
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 surgery
Risks/Benefits of Stents
Shorter procedural and recovery time than CABG
Angina relief about 75% of the time
Decreases the risk for heart attack
Increases blood flow to the heart
Risks and Limitations:
Risk of death <1%
Risk of heart attack, thrombosis and bleeding <4%
Major limitation of procedure is a high rate of restenosis and need for revascularization
Scar tissue formation
Not a cure to the disease, still need to reduce risk factors and make lifestyle changes to prevent future disease progression
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 artery
This procedure is performed with assistance of a heart-lung machine, which supports the patient’s blood during surgery
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 form
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 dysfunction
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 stem CAD
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 patients
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 Patient?
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 PCI
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. 12.8%)
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 days earlier
This technique may develop into new technology that might be used more often in the future and may replace open heart surgery
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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