Why do I need a coronary angiogram after a cardiac CTA?

Hello everyone, I'm Dr. Cardiovascular House.

Recently, the question was asked, why do I need to have a coronary angiogram after cardiac CTA?

Today we're going to talk about that!

By the way, what we call cardiac CTA in our daily mouth usually refers to coronary CTA, that is, coronary CT angiography.

First of all, let's understand, what is coronary CTA and why do coronary CTA?

Coronary CTA stands for Coronary CT Angiography, which is a method that uses computed tomography (CT) technology to visualize the cardiovascular system. CTA combines CT scans and angiography to create non-invasive, high-resolution vascular imaging. It is clinically used to evaluate vascular lesions and diseases. So why do cardiac CTA?

The main purpose is to check whether there is a lesion in the coronary artery, the severity of the lesion, and the specific location of stenosis, so as to identify and diagnose coronary heart disease. So, what is coronary heart disease?

Coronary heart disease is called coronary atherosclerotic heart disease, which refers to the heart disease caused by atherosclerosis of the coronary arteries, resulting in myocardial ischemia, hypoxia, or necrosis, referred to as coronary heart disease, also known as ischemic heart disease.

At present, in clinical practice, the narrowing of the diameter of the lumen of the coronary artery by more than 50% is called coronary atherosclerotic heart disease, and the stenosis of less than 50% is called coronary atherosclerosis.

The next question is, why do some people need to have a coronary angiogram after they have done cardiac CTA?

Here, I have to say again, what is coronary angiography?

Coronary angiography is through the femoral artery, radial artery or other peripheral arteries, insert a catheter, and send to the ascending aorta, and finally placed at the left and right coronary artery openings, injected with iodine contrast agent, so that the coronary arteries present dynamic development, for live recording, that is, while recording, so that the anatomical morphology of the coronary arteries and the location, degree and extent of obstructive lesions can be accurately revealed. Different from coronary CTA, it is a static image of coronary artery blood vessels by intravenous injection of iodine contrast medium, multi-detector CT is used to image the coronary artery vessels, and the image is formed by computer processing technology, that is, the three-dimensional reconstruction is carried out by the computer in the later stage, which is a static image. Therefore, coronary angiography is the gold standard for diagnosing coronary heart disease and is a live record, while cardiac CTA is a three-dimensional reconstruction by computer. According to a large number of clinical data, the accuracy rate of cardiac CTA is about 80%.

Now, to answer the question of why some people need further coronary angiography after having a cardiac CTA.

First, if CTA finds that there is a serious coronary artery lesion, then further coronary angiography is needed to further accurately determine the location of coronary artery stenosis, the severity of the stenosis, and the length of the lesion, so as to further evaluate whether cardiac stent implantation or heart bypass surgery is needed**. Second,Although some people have done CTA and the results show that there is no severe stenosis, they have repeated angina symptoms, such as chest tightness, chest pain, palpitation, etc. Further coronary angiography is required because cardiac CTA has an error of about 20%. Many people still don't understand this, so let me put it another way.

If a person has stomach pain, the doctor recommends a barium swallow fluoroscopy of the digestive tract, and the results indicate that gastric polyps are possible, which requires further gastroscopy to see if there are gastric polyps, as well as the location and number of gastric polyps. In the same way, cardiac CTA is equivalent to barium swallow fluoroscopy of the digestive tract, coronary angiography is equivalent to gastroscopy, and stent implantation** is equivalent to gastric polyp removal**. In summary, cardiac CTA is to initially check whether there is coronary artery stenosis, if there is no stenosis, coronary artery disease is ruled out, if there is severe stenosis, further coronary angiography is required to confirm the diagnosis, and if there is severe stenosis, cardiac stent implantation or heart bypass surgery may be required**.

Let's analyze this problem through a case!

The patient, a 58-year-old middle-aged and elderly man, was admitted to the hospital with "chest tightness and shortness of breath for more than a year after repeated activities, which worsened for one week". Previous history of hypertension, irregular medication, denial of diabetes mellitus, and long-term smoking.

According to the results of this cardiac CTA report, the patient's coronary heart disease was not serious, and conventional drugs were sufficient, but the patient was re-angina pectoris, so he was admitted to the hospital for further coronary angiography.

2023-06-09 coronary angiography examination, the results suggested: mild plaque in the proximal segment of LAD, mild plaque in the distal segment of LCX, diffuse lesion in the middle segment of RCA, and about 90% stenosis.

Comparing the results of cardiac CTA and coronary angiography, it can be seen that the two reports are very different, and they are completely one in the sky and one underground.

First, cardiac CTA suggests moderate to severe stenosis of the proximal segment of LAD, but coronary angiography results suggest mild plaque of the proximal segment of LAD, i.e., slight stenosis. Second, cardiac CTA indicates that RCA is completely normal, but coronary angiography shows severe stenosis of the middle of RCA, about 90%, and it is worth reminding that coronary artery diameter stenosis of 90% corresponds to a 99% reduction in area. Therefore, in the case of this patient, it is clear that there is insufficient blood supply to the myocardium, so when the patient is active and tired, there will be obvious angina symptoms. At present, the diagnosis of the patient is clear, and his first plan is to undergo further coronary artery stent implantation on the basis of the first drug, and the operation is smooth. After the operation, the patient recovered well, and later returned to the outpatient clinic for many times, all of whom complained of no further symptoms such as chest tightness and wheezing.

Below, let's take a closer look at the contrast images of this patient before surgery and after stenting.

Post-operative angiography:

Combined with the patient's coronary angiography images, the reason for the error between cardiac CTA and coronary angiography can be preliminarily analyzed.

First, let's look at the patient's LADThat is, the left anterior descending artery, it can be found that the distal blood vessels of the LAD have changed, and the blood vessels that originally belonged to the main branch have become branches, and the branch blood vessels have become the main branches. Let's take a look at RCA, or right coronary arteryIt can be found that the stenosis in the middle of the LAD is reticular stenosis, and the shape of the blood vessel is still there, but the internal blood flow is very slender, so when the CTA of the heart is reconstructed in 3D, it is considered that there is no stenosis in the area. Based on the above, because coronary angiography is a real-time dynamic ** image, it can be understood as a live broadcast, while cardiac CTA is a three-dimensional reconstruction after shooting, which is a static image, so the results of coronary angiography are very accurate.

It should be noted that there is a one-year interval between cardiac CTA and coronary angiography, and although the disease can progress significantly within one year, this case is only a case study and does not represent all cases.

At this time, some people questioned, since it is so troublesome, why not do it in one step and do a coronary angiography directly?

First of all, cardiac CTA is fast, convenient, cheap, and can be checked without hospitalization, and you can go home after doing it in the outpatient clinic. At present, the cost of coronary angiography is about 3500 4000 yuan, while the cost of cardiac CTA is about 900 1000 yuan, which varies slightly due to regional differences or some consumables**. Secondly, cardiac CTA is a non-invasive examination, with a high safety factor and basically no complications. Coronary angiography is a minimally invasive examination, and from another level, it is a first-class operation, which has certain risks, but the current technology is very mature, and its safety is very guaranteed. In general, coronary angiography requires hospitalization to be scheduled, and at least one day of observation is required at the end of the day before returning home. Thirdly, in addition to coronary arteries with severe calcified lesions, slow blood flow, or local malformations, the accuracy rate of cardiac CTA can also reach more than 90%. Fourth, in coronary angiography, some patients have abnormal opening of the right coronary artery, and the surgeon will have a headache and cannot find the opening of the right coronary artery, so selective coronary angiography cannot be performed, while cardiac CTA can find the right coronary artery with its abnormal opening, and can determine whether the coronary artery is stenosis and the degree of stenosis. Wait a minute. Finally, to sum up, should we choose cardiac CTA or coronary angiography?Who's the best?

In fact, there is no strict clinical choice, and it is not said who is better, and it is not necessary to choose cardiac CTA, or coronary angiography must be chosen.

If the male is over 45 years old, the female is over 60 years old, and there are multiple coronary heart disease risks, such as hypertension, diabetes, hyperlipidemia, obesity, smoking, mental stress, family history of coronary heart disease, etc., and there are coronary heart disease symptoms, such as chest tightness, chest pain, fainting, toothache during activity, neck pain, etc., coronary angiography is recommended for clarification. Conversely, for patients who are young and do not have multiple risk factors for coronary artery disease, cardiac CTA examination can be preferred for coronary artery evaluation, and if a serious coronary artery problem is found, coronary angiography can be performed to confirm the diagnosis.

Well, that's the end of today's explanation. I'm Dr. Cardiovascular House.

If you have any questions, please leave a message in the comment area.

I wish you all a happy life and good health.

Disclaimer: This article is only for popular science publicity, not for disease diagnosis and **. If you have relevant clinical symptoms, please go to the hospital in time**.