Doctors use risk factors such as smoking, high blood pressure, high cholesterol, diabetes, body-mass index, gender and age to help determine the likelihood someone will suffer a future heart attack.
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However, risk prediction is an inaccurate science. Too often, someone thought to be at low or intermediate risk has an unexpected heart attack or dies from the malfunctioning of their heart’s electrical system (sudden cardiac death). A noninvasive imaging test called coronary CT angiography (CTA) may identify these patients before it happens.
“CTA has emerged as a very useful test for risk prediction when used in the right patients,” says imaging cardiologist Milind Desai, MD.
A trustworthy test
CTA has two important qualities:
- It is sensitive, meaning it detects coronary heart disease with a high degree of accuracy
- It has high negative predictive value, which means it accurately identifies people who don’t have the disease.
These qualities make CTA valuable for use in patients admitted to the Emergency Department with chest pain. “A normal CTA generally means the patient can confidently return home in a timely manner. On the other hand, a patient with significant coronary disease can be quickly identified and admitted for treatment,” says Dr. Desai.
Where else CTA is useful
Coronary CTA is also helpful for patients:
- Considered at intermediate risk and suffering from angina
- Considered at low or intermediate risk with no history of coronary heart disease and newly diagnosed with heart failure
- Considered at intermediate risk and about to undergo noncardiac surgery
- Whose ECG, exercise and stress imaging test results do not match
- Who have new or worsening symptoms of heart disease, whose past stress imaging study was normal
- Needing follow-up after the left main artery is stented
When CTA is the wrong test
Coronary CTA is not a good screening tool for heart disease in people without symptoms. Image quality tends to be poor in obese patients and those with heavily calcified arteries, high or irregular heart rates and small stents.
As yet, coronary CTA is not the right test for patients considered at high risk based on prior test results, prior revascularization or multiple risk factors. “These patients are more suitable for a cardiac catheterization,” says Dr. Desai.