Download What is Coronary Artery Disease (CAD)?

What is Coronary Artery Disease (CAD)?
Author: Kacy S. Jones, MSN, ACNP
August, 2012
Coronary artery disease is a chronic build up of plaque in the arteries of the heart,
also called the coronary arteries. This process is also called atherosclerosis. Over
13 million Americans suffer from this chronic disease (1). According to the CDC,
heart disease is the leading cause of death among men and women and accounts
for nearly one fourth of all deaths in the United States (2).
What are the risk factors?
-Advanced age
-Smoking
-Hypertension
-High cholesterol
-Diabetes
-Obesity
What are the symptoms?
-Mental stress and depression
-Pain, aching, tightness, or discomfort in
-Family History
the chest or between the shoulder blades
-Shortness of breath
-Fatigue
-Numbness or tingling in the chest, arms, neck or jaw
-Passing out
-Decreased exercise tolerance
-Nausea or sweating may also accompany some of the above symptoms
How is it diagnosed?
The gold standard for diagnosing coronary artery disease is a cardiac
catheterization. This is a procedure in which a cardiologist places a catheter into
the artery of the groin or arm and injects a contrast dye to view the arteries. It is
the same procedure in which a stent is placed as well. This study is able to show if
there is arterial blockage and if so, how much. There are several other studies
usually done leading up to this test and that may also be beneficial in diagnosing
the disease. These tests include an EKG, blood work (cholesterol, cardiac enzymes
etc.), echocardiogram, stress test, and a CT angiogram.
How is CAD treated?
Medical Therapy:
Coronary artery disease is a progressive disease and requires continuous
treatment with medication and lifestyle changes. Exercise, smoking cessation, and
weight loss are high on the list of treatments and are just as important as
medications. Medications in many cases are just as important as the procedures
such as receiving a stent or undergoing bypass surgery. There are several
medications that may be used. Aspirin is used for all patients unless it is
contraindicated for that individual. Another blood thinner called an antiplatelet
may be used in conjunction with aspirin or in aspirin intolerant individuals. There
are currently three of these on the market: Plavix (Clopidogrel), Effient
(Prasugrel), or Brilinta (Ticagrelor). These drugs are usually started after a heart
attack or after a stent is placed, but may also be prescribed in chronic disease to
help prevent future events for high risk patients like diabetics.
Statins are a class of drugs that primarily lower cholesterol but have been shown
to decrease the risk of heart attacks and slow the progression of the disease. This
class of drug has properties which reduce inflammation in the arteries and also
decrease the propensity to form blood clots in patients with coronary artery
disease . This leads to an increase in survival and a decrease in future coronary
events. Therefore, it is recommended that all patients be given a statin that have
CAD regardless of what their cholesterol level is . The goal for LDL reduction is less
than 100 mg/dL and possible even less than 70 mg/dL . (2). There are several
drugs in the class and they are listed here: Zocor (Simvastatin), Lipitor
(Atorvastatin), Crestor (Rosuvastatin), Pravachol (Pravastatin), Lescol
(Fluvastatin), Mevacor (Lovastatin), and Livalo (Pitavastatin). There are also
several combination drugs that may have a statin in them that are not listed here.
Beta Blockers are very commonly used to treat CAD. They have many benefits
included lowering blood pressure, lowering heart rate and the oxygen demands
on the heart, preventing abnormal heart rhythms, preventing future heart
attacks, and improving heart function in hearts that have been damaged. In
patients that have had a heart attack, giving a beta blocker can reduce mortality
by 13 percent, reduce future heart attack by 22 percent, and prevent cardiac
arrest in 15 percent. If the heart rate or blood pressure is too low, beta blockers
can become harmful, but when given to appropriate patients the results are
amazing. A list of the more commonly used beta blockers today is provided here
but it is not extensive: Coreg (Carvedilol), Toprol XL (Metoprolol succinate),
Metoprolol (Metoprolol tartrate), Bystolic (Nebivolol), Tenormin (Atenolol),
Betapace (Sotalol), Zebeta (Bisoprolol). (2).
Ace Inhibitors are another very important drug class for patients with CAD,
especially in patients with heart failure. This drug class has been shown to prevent
ventricular remodeling which can occur with a heart attack or with chronic heart
disease over time. Remodeling of the ventricle leads to heart failure and
ultimately shorter life expectancy. Many trials have shown these drugs reduced
mortality in patients with heart attacks, especially when there is left ventricular
dysfunction. Because of how these drugs work on the body, sometimes a side
effect is a dry cough. If this should occur, usually a drug from another class with
similar benefits can be prescribed called an ARB. They are contraindicated in
pregnancy, some cases of renal failure, and if the blood pressure is too low. There
are several drugs that fall into this category and here is a fairly extensive list:
Zestril (Lisinopril), Altace (Ramipril), Vasotec (Ramipril), Mavik (Trandolapril),
Lotensin (Benazapril), Accupril (Quinapril), Monopril (Fosinopril), Capoten
(Captopril). (2).
Nitrates serve an important role in treating CAD as well. These drugs relax the
vascular smooth muscle (including the arteries and veins) which in turn takes
some workload off the heart. In many patients with chronic chest pain, or angina,
nitrates can significantly improve exercise tolerance and improve quality of life.
For patients with infrequent chest pain, the short acting nitrate called
nitroglycerin is preferred using the sublingual route (under the tongue). This route
bypasses the normal metabolism and takes effect in usually less than 5 minutes.
However in patients that have frequent symptoms of chest pain, a longer acting
formulation may be prescribed called Imdur (Isosorbide). Side effects may
include dizziness, headache, or low blood pressure. The low blood pressure can
be life threatening if a nitrate is taken with the erectile dysfunction drugs such as
Viagra or Levitra. (2).
Calcium channel blockers work different than the nitrates but have a similar effect
and many times used in conjunction with them. These drugs relax and dilate the
arteries by interacting with the calcium channels. They are especially effective in
chest pain that is caused by a vasospasm but useful in chest pain from CAD as
well. Generally they are great at reducing blood pressure in addition to their
antianginal properties.
In most patients, beta blockers are still first line, but in most some cases, they
may be added to beta blockers, or used in patients that do not tolerate beta
blockers. There are two generations of these drugs. The first generation includes
Nifedipine(Adalat), Cardizem (Diltiazem), and Verapamil (Veralan, Calan). This
class is generally contraindicated or has to be used very carefully in heart failure
patients. Amlodopine (Norvasc) is a second generation calcium channel blocker
that is safe to use in heart failure patients which makes it the drug of choice in
many cases. (2).
Ranolazine or Ranexa stands by itself in the treatment of CAD. This is the newest
drug approved for the treatment of chronic angina or chest pain associated with
CAD. It has been on the market since 2006 and is generally reserved for last line
therapy in patients with persistent symptoms despite being on the medications
listed above. One benefit to Ranolazine is that it does not have a significant effect
on blood pressure or heart rate, which is unlike the other drugs we have talked
about. The exact mechanism is unknown but it is also thought to work at the
cellular level on calcium and sodium channels. Since it has been on the market, it
has also been shown in some cases to decrease abnormal heart rhythms in this
patient population. It is currently being studied for this reason. (2).
Interventional Therapy:
Interventional therapy involves Percutaneous Coronary Intervention (PCI) or
Coronary Artery Bypass Surgery (CABG). PCI includes any of the procedures that
are done in the catheterization lab with a catheter such as angioplasty or stent
placement.
The picture to the left shows a significant stenosis in
the artery. The next picture is the catheter with a
balloon which inflates to make room for the stent.
This is called angioplasty. Then the stent is able to be
placed in the artery and keep the artery open and
the plaque up against the artery wall. However, CAD
is a progressive disease and the process will continue
to occur which is why medications and lifestyle
changes are so important. Some individuals need
multiple stents in their lifetime as well.
PCI is done in the cardiac catheterization lab or cath lab for short. Vascular access
is usually obtained from the artery in your groin or in your arm. Once the catheter
is placed into the artery, it is gradually progressed upwards until the cardiac
vessels are reached. Then a small amount of dye called contrast is injected into
the arteries so the cardiologist is able to see if there is any significant blockage
present. If there is blockage that is able to be fixed with angioplasty and stent
placement then another catheter will be placed to do so. The entire procedure
usually takes about an hour but could be longer depending on how many
interventions need to be completed.
If there are too many blockages or blockages unable to be fixed with a stent, then
coronary artery bypass grafting may be recommended. CABG is performed by a
cardiac surgeon in an operating room under general anesthesia. In many cases
the heart is stopped and placed on a “pump” but in some cases the surgery may
be done “off pump” with the heart still beating. Either way, usually a vein is
harvested from the leg and an artery is used from the chest wall to bypass around
the blockages. The picture below illustrates this perfectly.
However, the same disease process can still affect the bypass grafts over time
which is why lifestyle modification and medication compliance are so important.
This is a brief summary of the CAD and its medical treatment. For more
information or specifics on certain procedures or aspects of the disease process,
please search the other articles in the library or email us about a topic that you
would like us to write about. Thank you for visiting HeartHelp.
References:
1. CDC (March, 2012). Heart Disease Facts. Retrieved from
http://www.cdc.gov/heartdisease/facts.htm/
2. Braunwald, E., Libby, P., Bonow, R., Mann, D., & Zipes, D. (Eds.) . (2008). Braunwald’s
Heart Disease, A Textbook of Cardiovascular Medicine. Philadelphia, PA: Saunders
Elsevier