Coronary CTA

One of the more recent developments in imaging technology is Computed Tomography Coronary Angiography, or CCTA, a minimally invasive way to visualize the blood vessels.

"This is an important advance for patients with undiagnosed coronary artery disease (CAD)," says Lara B. Eisenberg, MD, "because CTCA can identify the condition even before a patient experiences noticeable symptoms. This allows physicians to take steps to treat this disease in its earliest stages, before it can cause a heart attack."

About CAD
Coronary artery disease is the most prevalent disease in the United States, causing 650,000 deaths each year.

CAD develops when fatty deposits, debris, calcium, and cholesterol accumulate in the wall of the blood vessels supplying the heart muscle. These areas are called plaques.

"In this early stage of CAD, there is often little or no narrowing of the coronary blood vessels," informs Dr. Eisenberg, "so traditional angiography, which looks for a blockage or narrowing of the coronary arteries, may not detect the condition." For these patients, the first and only symptom of CAD they may experience is a massive, fatal heart attack.

Vulnerable PlaquesSome plaques have a thinner wall which makes them more prone to rupture. These are called vulnerable plaques.

If a plaque ruptures, the debris inside can cause a clot to form which can block one of the arteries supplying the heart muscle. The decreased blood flow to the heart muscle is what is called a heart attack and, if severe enough, can cause sudden death. If the ruptured plaque does not block the blood vessel, the plaque may heal by hardening or calcifying. This can narrow the blood vessel which decreases blood flow to the heart muscle but less severely than when a clot suddenly blocks the vessel.

Chest pain, shortness of breath, and fatigue, especially with exercise, are common symptoms of narrowing of the coronary arteries, and it is this later stage of CAD that is often detected by traditional angiography. Millions of patients diagnosed with CAD are managed medically, at a cost of more than $30-billion annually.

How CTCA helps
"CT coronary angiography is the best non-invasive test available for looking directly at the coronary arteries," states Dr. Eisenberg. "With CTCA, we not only see narrowing of the coronary arteries, but also see the plaques in their early stages."

CT angiography has been shown to be 95% sensitive in detecting CAD, and to have a 98% accuracy rate in ruling out the disease.

In most cases, angioplasty (a procedure that reopens blocked vessels) and/or stenting is not indicated until a coronary artery is narrowed by as much as 70%. Even so, it is important to identify early stage CAD because it can alert a physician to the need to prescribe statin drugs. (i.e. Lipitor, Crestor, etc)

Statin drugs speed the maturation of plaques, making them less vulnerable to rupture. These drugs have been shown to decrease the risk of heart attack in high risk patients by more than 50%. They also decrease the risk of heart attack for patients with normal cholesterol levels by approximately 20%.

Go to http://hp2010.nhlbihin.net/atpiii/calculator.asp?usertype=pub for a quick way to assess your 10-year risk of experiencing a heart attack.

Who should be tested with CTCA?
CTCA may be indicated when a patient has one or more of the major risk factors for coronary disease. These risk factors include:

  • Current tobacco use
  • Hypertension (>140/90)
  • Elevated LDL (>130)
  • Low HDL (<40)
  • Diabetes
  • Strong family history of CAD
  • C-reactive protein, inherited syndromes

Contraindications for CTCA include:

  • Lack of risk factors
  • Allergy to the contrast agent if medications fail to control reaction
  • Atrial fibrillation
  • Pacemaker
  • Kidney failure

Preparing for CTCA
Patients preparing for a CTA study should avoid caffeine in any form (caffeinated coffees, teas, soft drinks, etc.) for 12 hours prior to the exam, and should take no solid food for 4 hours prior to the exam.

Prior to the test, the patient receives one dose of a beta blocker.

An IV line will be placed, and a contrast agent will be delivered through the line.

A single dose of nitroglycerine spray will be given under the tongue.

During CTCA
During CT coronary angiography, the patient lies quietly on a table that moves through a doughnut-shaped machine called a "gantry."

As the patient moves through the gantry, an x-ray beam and x-ray detector rotate around the patient, creating a series of cross-sectional images of the heart and the blood vessels supplying it. The patient will be asked to hold his or her breath several times while images are obtained. The last part of the exam, when the most important images of the heart are obtained, is usually acquired in just 5 heartbeats.

The cross-sectional images are transferred to a computer that uses specialized software to "reassemble" the cross sections, delivering a multidimensional view of the coronary arteries. Because of the contrast agent, the blood vessels appear very bright, with blockages and plaques that can be identified by a radiologist skilled in reading these images.

Performed on an outpatient basis, CTCA takes less than 30 minutes to complete, so a patient can expect to spend about an hour at the imaging center.

Covering the cost of CTCA
CT coronary angiography is a highly sophisticated test, using leading edge technology, expensive medical equipment, and specialized computer software.

We only perform CTCA with a doctor's prescription.

Medicare and some insurers do cover the exam for specific indications. We provide the exam at a reasonable cost for those patients whose insurance does not cover the exam. Marcie Gaskins, R.N., our cardiac CT nurse, can answer questions you may have about the exam or schedule an exam. She can be reached at 301-896-3515.

CTCA Case Study Examples: