Can CTA help reduce risk for heart attack?

When is coronary computed tomography angiography (CTA) appropriate? Can use of CTA for angina help reduce future risk of heart attack? These are some of the questions that were investigated by the SCOT-HEART trial.

• 4,000  patients with chest pain followed for five years.
• The addition of coronary CTA improved patient outcomes versus standard medical care alone.
• Discuss coronary CTA with your family doctor or cardiologist to get a referral.

According to follow-up results from this randomized, double-blinded Scottish study, published September 2018 in the New England Journal of Medicine, the use of CTA in addition to standard care in patients with stable chest pain resulted in a significantly lower rate of nonfatal myocardial infarction (heart attack) or death from coronary heart disease at five years than standard care alone.

From November 2010 to September 2014, over 4,000 patients between ages 18-75 with suspected angina – stable chest pain or discomfort – due to coronary heart disease were classified into two groups. The first group received standard medical care alone, while the second group received standard care plus CTA imaging. The goal of this trial was to examine the benefits of CTA on the diagnosis, management, and outcome of participants.

“Several studies in the past have shown a role of coronary CTA in determining whether the patient would need further workup with catheter angiography or if surgical treatment would ultimately be necessary. This multi-centre study shows that coronary CTA can be used as a clinical tool to help general practitioners or cardiologists better optimize medications and reduce the risk of unwanted outcomes like heart attack,” says Dr. Khalil Jivraj, a specialized cardiac radiologist with Mayfair Diagnostics.

WHY WOULD CTA BE NEEDED?

If you have chest pain, but are otherwise stable – you have no other symptoms that would indicate a heart attack or other type of health emergency – further investigation into the cause of pain is often the next step. Your health care practitioner has a variety of investigative and treatment options to choose from, such as lab work and medication therapy, in addition to imaging which includes exercise stress testing, myocardial perfusion imaging, CTA, etc. And, choosing an appropriate test or medication can be complicated.

A common cause of chest pain is coronary artery disease (CAD) – a buildup of plaque in the inner lining of an artery causing it to narrow or become blocked. When medical imaging is ordered to investigate for CAD, it often looks at how the heart functions under stress (echocardiogram, exercise stress testing, myocardial perfusion imaging). CTA is another imaging option that can non-invasively examine the coronary arteries using a combination of X-rays and computer technology to produce comprehensive, detailed images.

“CTA has a very high sensitivity, in the range of 95-99%, in ruling out CAD, which means fewer false positives. It’s a great clinical tool to optimize a patient’s management,” says Dr. Jivraj.

According to the SCOT-HEART trial, the use of CTA resulted in better optimization of medical therapy in addition to better stratifying patients for potential future need of catheter angiography with stent placement or surgery. It is important to note, in this trial over five years, the use of CTA did not increase the frequency of patients undergoing invasive catheter angiography when compared to the standard treatment group.

“Now that we have more long-term data, we can see the benefits of having CTA as a standard part of a patient’s cardiovascular workup when investigating stable chest pain. Ultimately, it’s about decreasing the risk of unwanted outcomes,” adds Dr. Jivraj.

HOW DO I GET A CORONARY CTA EXAM?

Mayfair Diagnostics offers community-based private CT services as a complement to the public health care system.

Through the public health care system, coronary CTA has some, but limited availability. Whether public or private, a coronary CTA must be requested by a health care practitioner. To determine what is recommended, patients and their doctors often review medical and family history, risk factors, and if there are symptoms, how long symptoms have been present and how they affect daily activities. If a private coronary CTA scan is indicated as a best next course of action for a patient, a requisition will be provided and the appointment can be booked.

WHAT ARE THE RISKS OF CORONARY CTA?

Radiation exposure from a coronary CTA scan is higher than that of standard X-rays, but the associated risk is still small. For example, the radiation exposure from one coronary CTA is around the exposure from the earth’s natural background radiation in one year. In most cases, the benefits of a coronary CTA, such as the early detection of a serious illness, significantly outweigh the small increased risk from radiation exposure. Coronary CTA also has the small possible risk of an allergic reaction to the contrast dye.

For more information on coronary CTA, please visit the exam page.

REFERENCES

Douglas, P.S., et al. (2015) “Outcomes of Anatomical versus Functional Testing for Coronary Artery Disease.” The New England Journal of Medicine 2015; 372: 1291-1300.

Newby, D. E., et al. (2018) “Coronary CT Angiography and 5-Year Risk of Myocardial Infarction.” The New England Journal of Medicine 2018; 379: 924-33.

Williams, M.C., et al. (2016) “Use of Coronary Computed Tomographic Angiography to Guide Management of Patients With Coronary Disease.” Journal of the American College of Cardiology 2016; 67 (15): 1759-68.