Coronary CTA (computed tomographic angiography) is a new method of CT ("CAT") scan that can allow physicians to see otherwise invisible crucial blood vessels in the heart. These are the same vessels that are diseased in patients with atherosclerosis, or "hardening of the arteries".
 
Background

Coronary Artery Disease (CAD) is the number one killer of all people, causing the death of more people each year than all forms of cancer combined. For decades, various imaging methods have been used to diagnose CAD, with the "best" method being heart catheterization ("heart cath" or "cardiac cath"). This imaging method is a form of "angiography", or visualization of blood vessels, that allows a physician to "see" the small blood vessels that bring life-giving nutrients and oxygen to the heart (coronary arteries). When these become blocked quickly, the experience is called a "heart attack". If these blood vessels become narrowed by atherosclerosis ("hardening of the arteries"), the vital nutrients and oxygen that the heart needs may not be able to reach parts of the heart, causing it not to function correctly. This can be a cause of chronic heart disease, which is commonly experienced as "heart failure".
 
Narrowings or "blockages" in the coronary arteries are thus very important to detect, and in some cases, treat. Treatment commonly involves a process called "angioplasty" where a physician stretches open the narrowing/blockage, and may place a "stent" into the narrowed vessel to help keep it open. This procedure is performed during a heart cath, but not all heart caths include angioplasty or stenting.
 
Because heart caths are "invasive", they have risks. During a heart cath, the physician has to "enter the body" with a needle and small tube inserted into the thigh and threaded up into the heart. Entering the body in this manner has risks associated with it that "non-invasive" procedures do not. Non-invasive procedures, like CT ("CAT") scans, are always preferable to invasive ones. However, until recently, there has been no non-invasive test that was considered anywhere as good or as accurate as heart cath. Thus, there were no options for patients.
 
With the discovery of a new form of CT scan, called multislice or multidetector CT (MSCT or MDCT), patients and physicians now have a new method to examine the vessels of the heart without "invading" or entering the body. It is now felt that MDCT scanning of the heart, called "coronary CTA" may be a suitable replacement for heart cath in some patients. If you are reading this, you might be considering such an exam, or your physician might have recommended one to you. If so, read on, and hopefully your understanding of the procedure will help reduce any concerns you might have about it.
 
A coronary CTA is just like any other CT scan from the patients’ point of view. In other words, if you have already had a CT scan of your chest, abdomen, or pelvis, you have already experienced the examination. It is no different.
 
The difference between a coronary CTA and a regular CT scan is in the way the information is processed after you leave the facility. Computers take the image data and make very special images which were not possible just a few years ago. These special images are the ones that allow you physician to see the heart vessels.
 
The CTA Imaging Experience

A coronary CTA is just like any other CT scan from the patients’ point of view. In other words, if you have already had a CT scan of your chest, abdomen, or pelvis, you have already experienced the examination. It is only a little different. You will not be asked to drink any special fluids for this type of CT scan.
 
If you have never had a CT scan before, don’t worry, they are not bad at all. You will be asked to where a gown instead of clothing, and you will be asked to remove certain items of underwear. After reviewing your history, and making sure that it is safe to give you contrast, an IV will be placed into your arm, near the elbow joint. Contrast, sometimes called "dye", is required to perform coronary CTA.
 
Because the scanner is making pictures of your heart, if your heart is beating too fast, the pictures can be blurry, just like when you take a photograph of a moving object. The blurring can interfere with the radiologists’ ability to see the vessels in the heart, so we try very hard to get the heart to beat at a certain rate before we begin the study. To do this, you may be asked to take a medication, called a beta blocker, by mouth (pill) one hour prior to the scan. This will help slow your heart rate and make the pictures more accurate. If you are already on beta blockers for a heart condition or high blood pressure, don’t worry, you will likely not need more. Patients with asthma or reactive airways disease should inform the staff before any beta blocker is given.
 
Once you are ready, you will be placed on the CT scan table on your back. You will be made comfortable with pillows and blankets. The technologist will ask you to hold your breath as you pass into the CT scanner, which is shaped like a big donut. You will pass in and out of the donut hole several times during your exam, each time having pictures of a different type being taken as you pass in and out.
 
The first time you pass in and out, the CT scanner is analyzing your body to decide how best to make images for you. The next time, the scanner is taking pictures that will be used to determine how much calcium is present in your hearts’ blood vessels. This is called a "coronary calcium score" and this has recently been found to be very useful in predicting whether or not you are at risk of having a heart attack or stroke in the future.
 
Just prior to the third time you pass into the scanner, you will receive an injection of contrast through the IV in your arm. You will likely feel warm all over your body, or even taste a strange taste in your mouth. Most of the time, that is all you will feel, and the sensation will pass very quickly. During that time, the technologist will ask you to hold your breath again, and you will pass in and out of the scanner one last time. This is the time when the coronary CTA is being created.
 
The CTA Results

Because the images are so complex, they require special computers to process the information. Because this takes time, there are no immediate results that can be given to you. Your physician will receive the results as soon as the computers and the radiologist are done processing them, which is usually later the same day, or the next morning.
 
Who Should Consider a CTA?

Any consideration of coronary CTA should begin with a discussion with your physician.
 
Typically, a review of your medical and family history will allow your physician to use the Framingham Criteria to assess your risk of having significant coronary artery disease (atherosclerosis). If your risk is calculated to be less than 10%, then you are considered "low risk" and may not require further testing. If your calculated risk is between 10-20%, then you are considered "intermediate risk" and additional tests might be considered very valuable to further clarify your true risk. If your calculated risk is >20%, then you are already considered "high risk" for CAD and most likely will be advised not to have a CTA, but rather a heart cath.
 
As with all tests that use X-Rays to produce images, patients and their physicians should weigh the benefits versus the risks. X-Rays are a form of radiation and it is well established both medically and historically that exposure to radiation should be kept to a minimum in one’s lifetime. However, the radiation exposure in CTA is acceptable when it can help to avoid heart cath, which not only uses radiation, but also is invasive.
 
The most common reasons a physician would order a coronary CTA are as follows: 

• Exclusion of "anomalous" coronary arteries: Sometimes, people are born "different" from everyone else, and inside their anatomy is not the same. Many times, we can live our whole life and not know that we are different inside, while other times, the differences inside make us unhealthy. The same is true for the arteries of the heart. When they are not in the usual positions in the heart, they are called "anomalous". Some anomalous coronary arteries cause no problems, while others cause significant problems. CTA is the best method to confirm that the coronary arteries are located in the correct place.
• In patients who have intermediate to high-risk for coronary artery disease, but who do NOT have typical symptoms, like:
  • chest pain
  • shortness of breath
  • fatigue during heavy physical activity
• In patients who have low to intermediate risk for coronary artery disease, and unusual symptoms, such as:
  • chest pain unrelated to physical exertion
• In patients who have already undergone other tests of their heart to find coronary artery disease, but those results have been unclear or inconclusive.  

Who should not have a CTA?

To date, Coronary CTA has not been proven as effective as heart cath in detecting disease in the smaller heart arteries that branch from the larger coronary arteries. If your  physician is convinced that you have a narrowing of a heart artery that might be repairable by angioplasty (high risk by Framingham Criteria or other testing), (s)he may recommend that you undergo heart cath rather than coronary CTA. Such patients include those with a history of:

• chest pain during heavy physical activity
• positive stress-test results
• known history of coronary artery disease or heart attack.

Coronary CTA also is of limited use in patients with extensive areas of old calcified, or hardened, plaque, which is often the case in older patients. Patients who are extremely overweight or who have irregular heart rhythms also tend not to be suitable candidates for this test because the images are too blurry to be accurate.

Contraindications to CTA

Generally, patients who cannot undergo regular CT scanning should not be considered for coronary CTA. These include patients:

• who are pregnant
• who have irregular heart rhythms (such as atrial fibrillation)
• who have significant kidney disease
• who have severe diabetes (and thus kidney disease)
• who have past history of severe allergy to CT contrast:
  • however, with premedication, CTA can be considered…

β-blockade medication is required to undergo the examination (to slow your heart rate for optimal images). Therefore, some additional patients should be cautioned about undergoing CTA. These include patients: 

• severe reactive airways disease (asthma)
  • again, with premediation, CTA can be considered…

Some patients may undergo coronary CTA, but special precautions must be followed to optimize the examination and insure your safety. These include patients:

• who are taking Glucophage medication for diabetes (or some form of it)
  • after the CTA scan, patients will be given special instructions and /or medications

Pre Test instructions

• No caffeine for 24 hrs prior to the exam
  
• No food for 4 hours prior to exam
  
• Take all prescribed medications on time, as usual, with water only
  
• Bring a listing of all medications to your examination
  
• Be sure to let staff know of any allergies or if you suffer from asthma
  

Is coronary CTA covered by insurance?

Yes, but many insurance companies require precertification for the examination. Have your ordering physician review the indications with your insurance provider to better clarify if insurance will cover the expense for you.

How do I arrange to have a coronary CTA?

First, discuss the issue with your physician. There are many things listed above that (s)he can help to sort out, to better understand if coronary CTA is really for you. If you both decide that it is, your physician merely sends an order to Wake Radiology and we will schedule you at your convenience as soon as is possible.