Coronary CTA question

[Unregistered]

Given that the FAA does not accept CTA to exclude the presence of CAD. However, suppose it is being used in the setting of low risk findings that would otherwise be acceptable? Airman (3rd class) had episode of chest pain, is referred for stress imaging (echo), runs to 13+ METS and 90% predicted HR with normal results on imaging. Airman is not comfortable with this finding due to the character of the pain, asks for referral to interventional cardiologist who agrees that the pain sounds angina-like, recommends coronary CTA but offers to take him to the cath lab if the FAA demands a negative cath. Airman prefers the lower radiation dose and non-invasiveness of CTA but leans toward the cath thinking the FAA will ask for it even if the CTA is negative. Is this true, or will they disregard the CTA and simply accept the negative stress echo?

 

[Gary F]

Given that the FAA does not accept CTA to exclude the presence of CAD. However, suppose it is being used in the setting of low risk findings that would otherwise be acceptable? Airman (3rd class) had episode of chest pain, is referred for stress imaging (echo), runs to 13+ METS and 90% predicted HR with normal results on imaging. Airman is not comfortable with this finding due to the character of the pain, asks for referral to interventional cardiologist who agrees that the pain sounds angina-like, recommends coronary CTA but offers to take him to the cath lab if the FAA demands a negative cath. Airman prefers the lower radiation dose and non-invasiveness of CTA but leans toward the cath thinking the FAA will ask for it even if the CTA is negative. Is this true, or will they disregard the CTA and simply accept the negative stress echo?

Why not? Did you have chest pain when running on the treadmill? Cardiac chest pain should be most noticeable with heavy exertion. If you go looking for coronary artery disease that may not be causing symptoms then you might have a real problem with the FAA. Dr. Bruce may be willing to address this. Radiation from cardiac CT angiography is as high or higher than the radiation of a diagnostic cath.

 

[Unregistered]

Why not? Did you have chest pain when running on the treadmill? Cardiac chest pain should be most noticeable with heavy exertion.

Absolutely none. The pain came on at rest and lasted over 24 hours. Have had fleeting symptoms since, usually non-exertional (no pattern). But the character resembles angina (dull, diffuse, some radiation to the arms).

Radiation from cardiac CT angiography is as high or higher than the radiation of a diagnostic cath.

I thought so too, but the interventional cardiologist said that CTA dose would be 1-3 mSv, the cath more like 9-11. Maybe it varies depending on the facility?

 

[Gary F]

Absolutely none. The pain came on at rest and lasted over 24 hours. Have had fleeting symptoms since, usually non-exertional (no pattern). But the character resembles angina (dull, diffuse, some radiation to the arms).

I thought so too, but the interventional cardiologist said that CTA dose would be 1-3 mSv, the cath more like 9-11. Maybe it varies depending on the facility?

A coronary calcium score alone will give you 1-3 mSV and can provide useful information about the health of the coronaries but will not determine if the disease is flow limiting, that requires an angiogram (CT or heart cath and possibly a pressure wire study or IVUS). If you get a cornary angiogram with it expect an additional 6-12 mSv. Our average radiation dose here for combined calcium score and CT angiography runs about 11 mSV. This depends a lot on the equipment and technique and size of the patient. Heavier patients require a higher dose to get adequate images. I usually start with a coronary calcium score and have the tech call me if it is over 200 Agatston units and then decide to proceed with the CT angiogram. If the patient has a really coronary high calcium score (over 1,000) I will usually cancel the CT angio and proceed with a cath if there is a reasonable indication. A CT angiogram can be uninterpretable in the presence of significant coronary calcium while invasive angiogram (cath) is not affected by calcium.

A negative treadmill stress echo with over 10 METS and atypical symptoms would generally not require additional testing unless the symptoms persist or worsen. Typical angina is percordial chest pressure or tightness elicited by exertion and relieved by rest and that might justify an angiogram with a negative stress test. Atypical chest pain is pain which does not meet the criteria for typical angina and can't be explained by something else otherwise known as non-cardiac chest pain. Stress echo has about a 15% false negative rate however if you take into account exercise tolerance, the prognosis can be very good even if you have some coronary artery disease treated only with medical management of risk factors. As a general rule (stable patients) stents do not improve survival over medical management. CABG surgery can improve survival if someone has left main or multivessel disease but this would be unlikely with a negative stress echo with good exercise tolerance.

 

[Unregistered]

A coronary calcium score alone will give you 1-3 mSV and can provide useful information about the health of the coronaries but will not determine if the disease is flow limiting, that requires an angiogram (CT or heart cath and possibly a pressure wire study or IVUS). If you get a cornary angiogram with it expect an additional 6-12 mSv. Our average radiation dose here for combined calcium score and CT angiography runs about 11 mSV. This depends a lot on the equipment and technique and size of the patient. Heavier patients require a higher dose to get adequate images.

I am 100% sure that we were talking about a CT angiogram not just a calcium score. The purpose was to delineate the anatomy of my coronary arteries. We discussed many aspects of CTA vs cath and this cardiologist said that the proposed test had comparable sensitivity for detecting CAD to a diagnostic cath. I am fairly thin (BMI 22) and that was part of the reason he expected my radiation dose from CTA to be on the low end. Even so that is a huge gap between your numbers and his and I believe I need to ask some more questions, and maybe consult a physicist at the same facility.

Thank you for your input.

 

[Gary F]

I am 100% sure that we were talking about a CT angiogram not just a calcium score. The purpose was to delineate the anatomy of my coronary arteries. We discussed many aspects of CTA vs cath and this cardiologist said that the proposed test had comparable sensitivity for detecting CAD to a diagnostic cath. I am fairly thin (BMI 22) and that was part of the reason he expected my radiation dose from CTA to be on the low end. Even so that is a huge gap between your numbers and his and I believe I need to ask some more questions, and maybe consult a physicist at the same facility.

Thank you for your input.

If you are concerned about the radiation dose of a CT coronary angio call the technician who runs the machine. 1-3 mSv for a CT angio is really low so they are using technology well more advanced than what we have or somebody is mistaken. To get good quality images you need a good machine and technician, thin patient (22 BMI is great), low regular heart rate (50 to 60 is optimum) and absent or very low coronary calcium (less than 100 Agatston units).