A Coronary CTA is an imaging test currently undergoing rapid development
and evaluation for non-invasively determining whether either fatty deposits
or calcium deposits have built up in the coronary arteries, which supply blood
to the heart muscle. If left untreated, these areas of build-up, called plaques,
can cause heart muscle disease. Heart muscle disease, in turn, can lead to
fatigue, shortness of breath, chest pain and/or heart attack.
How does it Work ?
A Coronary CTA comes from a special type of X-ray examination. Patients undergoing a Coronary CTA scan receive an iodine-containing contrast dye as an IV solution to ensure the best images possible. Oral medication may be given to slow or stabilize the patient’s heart rate for better imaging results. During the examination, which usually takes about 15 minutes, X-rays pass through the body and are picked up by special detectors in the scanner? Typically, higher numbers (especially 16 or more) of these detectors result in clearer final images. For that reason, Coronary CTA often is referred to as “multi-detector” or “multi-slice” CT scanning. The information collected during the Coronary CTA examination is used to identify the coronary arteries and, if present, plaques in their walls with the creation of 3D images on a computer screen.
How is Coronary CTA different from other heart tests?
One of the most common heart tests is the coronary angiogram, or cardiac catheterization. This test is more invasive and requires more patient recovery time than Coronary CTA. Patients who receive coronary angiograms must have a catheter, or small transport tube, threaded into their coronary arteries, which run along the outside of the heart. The catheter typically is inserted into a blood vessel in the upper thigh and then maneuvered up to the coronary arteries. The catheter then is used to inject the iodine dye needed for the test, which uses X-rays to record “movies” of interior of the coronary arteries.
Although Coronary CTA examinations are growing in use, coronary angiograms remain the “gold standard” for detecting coronary artery stenosis, which is a significant narrowing of an artery that could require catheter-based intervention (such as stenting) or surgery (such as bypassing). On the other hand, this new technology has consistently shown the ability to rule out significant narrowing of the major coronary arteries and can non-invasively detect “soft plaque,” or fatty matter, in their walls that has not yet hardened but that may lead to future problems without lifestyle changes or medical treatment.
Who should consider Coronary CTA?
The single most important step for patients trying to determine whether they should consider a Coronary CTA is consultation with their cardiologist or primary physician. This is because some Coronary CTA uses are more appropriate than others, and the scan carries some risk from X-ray exposure (potential for stimulating cancer) and contrast dye exposure (allergic reactions and kidney damage).
Overall, Coronary CTA examinations have tended to help determine a lack of significant narrowing and calcium deposits in the coronary arteries, as well as a presence of fatty deposits. This has been found to be particularly valuable in asymptomatic patients with higher risk for coronary disease, in patients with atypical symptoms but intermediate risk of coronary disease, or in patients with unclear stress-test results. . As a result, Florida Cardiology currently supports the careful use of coronary CTA for patients who have:
Intermediate pre-test probability of CAD with chest pain syndrome and ECG uninterpretable OR unable to exercise
Intermediate pre-test probability of CAD with acute chest pain syndrome and No ECG changes and serial enzymes negative
Uninterpretable or equivocal stress test (exercise, perfusion, or stress echo)
Evaluation of suspected coronary anomalies
Assessment of complex congenital heart disease including anomalies of coronary circulation, great vessels, and cardiac chambers and valves
Evaluation of coronary arteries in patients with new onset heart failure to assess etiology
Evaluation of cardiac mass (suspected tumor or thrombus) in Patients with technically limited images from echocardiogram, MRI, or TEE
Evaluation of pericardial conditions (pericardial mass, constrictive pericarditis, or complications of cardiac surgery) in Patients with technically limited images from echocardiogram, MRI, or TEE
Evaluation of pulmonary vein anatomy prior to invasive radiofrequency ablation for atrial fibrillation
Noninvasive coronary vein mapping prior to placement of biventricular pacemaker
Noninvasive coronary arterial mapping, including internal mammary artery prior to repeat cardiac surgical revascularization
For these types of patients, CTA can provide important insights to the cardiologist and primary care physician into the extent and nature of plaque formation with or without any narrowing of the coronary arteries. Coronary CTA also can non-invasively exclude narrowing of the arteries as the cause of chest discomfort and detect other possible causes of symptoms. But again, initial consultation with the cardiologist or primary physician is the key for patients seeking to determine the appropriateness of Coronary CTA.
What or other indications for CTA?
CTA is also a valuable tool for evaluating vascular disease as mentioned below:
Evaluation of suspected pulmonary embolism
Evaluation of thoracic or abdominal aorta for suspected dissection or aneurysm or stent graft failure
Evaluation of carotid arteries and cerebral vasculature
Evaluation of celiac, mesenteric and renal arteries.
Evaluation of PVD in upper or lower extremity arteries
Who should not have Coronary CTA?
To date, Coronary CTA has not been proven as effective as the coronary angiogram in detecting disease in the smaller heart arteries that branch off the major coronary arteries. For that reason, Florida Cardiology physicians do not consider Coronary CTA as an adequate substitute for needed coronary angiography in patients with strong evidence of narrowing of the coronary arteries. Such patients include those with a history of chest pain during heavy physical activity, a history of positive stress-test results, or a 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 abnormal heart rhythms also tend not to be suitable candidates for this test because imaging quality is compromised.
Who interprets the results and how do I get them?
The cardiologist in conjunction with radiologist will interpret the results. The results will be discussed with the patient by the cardiologist or by the primary care physician, depending on who ordered the test.
Florida Cardiology uses a state-of-the-art 64 Slice multi-row detector CT scanner;
Toshiba Aquilion 64 CFX
