Practice Changing: Non-invasive CT angio is a feasible alternative to the invasive conventional angiography for diagnosing complex CAD and decision-making

Coronary angiography is the gold standard diagnostic technique, which helps in therapeutic decision making in coronary disease. Coronary CT angiography is also a valuable aid to assess coronary heart disease. But, it has not been so widely used as the invasive coronary angiography.

But, the SYNTAX III REVOLUTION trial has now demonstrated that the non-invasive coronary CT angiography is non inferior to the invasive coronary angiography in diagnostic value.

The SYNTAX III Revolution trial for the first time randomised two separate Heart Teams (in six participating international centres) and not the patients, to quantify the anatomical complexity by using the SYNTAX score in patients with known de novo left main or three-vessel CAD in six participating international centres using information obtained from either coronary CTA or conventional angiography.

The primary goal was to assess the treatment decision, whether to decide on percutaneous coronary intervention (PCI), coronary artery bypass grafting (CABG) or equipoise between CABG and PCI.. The primary endpoint of this study was agreement between the two heart teams on the revascularization strategy.

Heart Team A had to make their decision on whether to perform revascularization with either PCI or surgery using information received strictly from the non-invasive multislice coronary computed tomography angiography (MSCT) from a GE Revolution multislice CT scan along with fractional flow reserve (FFR) CT assessment (HeartFlow).

Heart Team B also needed to make the same decision but using only conventional angiography.

·         No significant differences in the number of coronary stenoses > 50%, and SYNTAX score calculated by using coronary CTA and conventional angiography, were observed (1108 vs 1073 and 33.9 ± 12.0 vs. 30.3 ± 12.2, respectively).

·         CABG was recommended in 28% of patients by coronary CTA and in 26% of patients by invasive coronary angiography.

·         Equipoise CABG or PCI was suggested in 106 patients, with no difference between CTA and coronary angiography. Overall, the heart teams agreed on the coronary segments to be revascularized in 81.1% of cases.

FFRCT was available in 868 of the 1108 lesions and identified no flow-limiting stenosis in 116 lesions in 34% of the patients; thus, changing the treatment decision in 7% of the patients (the surgical procedure was changed to a percutaneous approach in 13 patients) and reducing the proportion of patients with haemodynamically significant three-vessel disease from 92.3 to 78.8%.

The European Society of Cardiology Guideline recommends coronary CTA as a class IIa indication in the presence of a low–intermediate pre-test probability risk of CAD.

These results from the SYNTAX III Revolution trial show that non-invasive multislice CT scans may well be the future in diagnostic imaging to assess the extent of coronary disease, whether it is a one-vessel or multivessel disease, and to guide decision-making accordingly regarding the revascularization strategy to adopt.

The results of the trial are published in the European Heart Journal. 

Dr KK Aggarwal

Padma Shri Awardee

President Elect Confederation of Medical Associations in Asia and Oceania   (CMAAO)

Group Editor-in-Chief IJCP Publications

President Heart Care Foundation of India

Immediate Past National President IMA

Heart attack with normal angiography or normal post mortem

Dr KK Aggarwal

Recipient of Padma Shri

The death of actress Sridevi was due to accidental drowning in a bath tub following loss of consciousness in a hotel in Dubai. This was the conclusion of the post-mortem report and foul play has been ruled out. Dubai police said that the case has been closed.

However, the cause of unconsciousness has not yet been conclusively found. Traces of alcohol were found in blood, and it has been suggested that this may have led to the accidental drowning.

Though the post mortem has ruled out heart attack, it still remains the most likely initiating event for loss of unconsciousness or gasping, which may have been due to ventricular tachycardia/fibrillation.

So, can one have a normal angiography or normal post-mortem after a heart attack? The answer is yes.

There are two types of heart attacks: Type I versus type II heart attack.

Most patients with acute heart attack will have obstructive (blockages) atherosclerotic (cholesterol deposition) coronary artery stenoses (narrowing) with acute thrombosis (clot) as the underlying pathology.

However, some patients (up to 28%) will not have significant epicardial coronary artery disease when coronary angiography is performed or post mortem is done. These patients are defined as having a type 2 heart attack, which is defined as a heart attack consequent to increased oxygen demand or decreased supply (coronary endothelial dysfunction, coronary artery spasm, coronary artery embolus, tachy / bradyarrhythmias, anemia, respiratory failure, hypertension, or hypotension).

Dr KK Aggarwal

Padma Shri Awardee
Vice President CMAAO
Group Editor-in-Chief IJCP Publications

President Heart Care Foundation of India

Immediate Past National President IMA

#AskDrKK: What is the treatment of choice – angioplasty or bypass surgery in young people?

#DrKKAnswers: Routine coronary angiography is not recommended in young patients with stable heart blockages, however, when indicated, both angioplasty and bypass surgery are effective and associated with lower risk in younger patients compared to older patients. Long term outcome of angioplasty is good  and bypass surgery is easier to perform. 

Ask Dr KK:How is CT radiation comparable to X ray Chest?

The dose from a single abdominal CT scan is comparable to the collective dose of 400 chest x-rays or natural background radiation for three years. 

About the author: Dr K K Aggarwal is Padmashri and Dr B C Roy National Awardee, President Heart Care Foundation of India, Dean Board of Medical Education Moolchand Medcity, Sr. Physician & Cardiologist, Visiting professor Clinical Research DIPSAR, Past President Delhi Medical Association, Past Academic and Research Wing Head IMA, Chairman Ethics Committee Delhi Medical Council.  

Ask Dr KK:How to counsel about diagnostic radiation to a patient?

All patients should be given a general idea about the magnitude of the proposed radiation dose. The exposure should be compared with an estimated effective dose to a single chest x-ray (0.02 mSv), a transcontinental airplane flight (0.02 mSv), or annual individual radiation dose from the natural background (3.0 mSv). 

About the author: Dr K K Aggarwal is Padmashri and Dr B C Roy National Awardee, President Heart Care Foundation of India, Dean Board of Medical Education Moolchand Medcity, Sr. Physician & Cardiologist, Visiting professor Clinical Research DIPSAR, Past President Delhi Medical Association, Past Academic and Research Wing Head IMA, Chairman Ethics Committee Delhi Medical Council.  

Ask Dr KK: Can CT cause cancer?

Use of CT may account for 1.5 to 2 percent of all future cancers in the United States.

The 2006 Biological Effects of Ionizing Radiation VII lifetime attributable cancer risk model predicts that 1 in 1000 persons exposed to 10 mSv (single diagnostic CT scan of the neck, chest, abdomen, or pelvis) will develop cancer due to that single exposure.

The lifetime attributable cancer mortality risk attributable to a single radiation exposure in a one year-old child is 1 in 550 following an abdominal CT and 1 in 1500 following a brain CT.

It has been estimated that 29,000 future cancers could be attributed to CT scans performed in the US in 2007 alone.

1 in 500 women and 1 in 660 men will develop cancer from their abdominal CT scan if the procedure is performed at the age of 20.

A 45 year-old adult undergoing one single full-body CT procedure would accrue an additional lifetime attributable cancer mortality risk of 0.08 percent from a single scan.

The lifetime attributable cancer mortality risk is 1.9 percent lifetime for thirty years of annual scans.

About the author: Dr K K Aggarwal is Padmashri and Dr B C Roy National Awardee, President Heart Care Foundation of India, Dean Board of Medical Education Moolchand Medcity, Sr. Physician & Cardiologist, Visiting professor Clinical Research DIPSAR, Past President Delhi Medical Association, Past Academic and Research Wing Head IMA, Chairman Ethics Committee Delhi Medical Council.  

Ask Dr KK: How common is multiple radiation exposures?

Multiple medical tests involving radiation exposure lead to high cumulative doses of radiation. In one study in 20 year period a heart patient may end up with 15 procedures involving radiation exposure. Of these four may be high dose procedures (≥3 mSv). The cumulative estimated effective dose from all medical sources exceeds 100 mSv in 31.4 percent of patients.

About the author: Dr K K Aggarwal is Padmashri and Dr B C Roy National Awardee, President Heart Care Foundation of India, Dean Board of Medical Education Moolchand Medcity, Sr. Physician & Cardiologist, Visiting professor Clinical Research DIPSAR, Past President Delhi Medical Association, Past Academic and Research Wing Head IMA, Chairman Ethics Committee Delhi Medical Council.  

Ask Dr KK: What is the exposure in a cardiac cath and EP study?

A typical X ray procedure results in a total effective dose of 8.3 mSv per hour of fluoroscopy.  The mean cardiac fluoroscopy time in managing paroxysmal atrial fibrillation is 57 minutes, atrial flutter is 20 minutes, ablation is 22 minutes and Pulmonary Vein isolation is 39 minutes.

About the author: Dr K K Aggarwal is Padmashri and Dr B C Roy National Awardee, President Heart Care Foundation of India, Dean Board of Medical Education Moolchand Medcity, Sr. Physician & Cardiologist, Visiting professor Clinical Research DIPSAR, Past President Delhi Medical Association, Past Academic and Research Wing Head IMA, Chairman Ethics Committee Delhi Medical Council.  

Dr KK Answers: How severe is background radiation?

The effective dose related to any radiologic procedure can be considered in the context of the annual effective dose to individuals from natural background radiation sources, including radon, cosmic rays, terrestrial, and internal sources. This background effective dose, approximately 3 mSv, does not pose a significant risk of future cancer to individuals.

About the author: Dr K K Aggarwal is Padmashri and Dr B C Roy National Awardee, President Heart Care Foundation of India, Dean Board of Medical Education Moolchand Medcity, Sr. Physician & Cardiologist, Visiting professor Clinical Research DIPSAR, Past President Delhi Medical Association, Past Academic and Research Wing Head IMA, Chairman Ethics Committee Delhi Medical Council.  

Ask Dr KK: What is the severity of radiation?

Mild exposure is called when the exposure is < 3 mSv, Moderate >3 to 20 mSv, High 20 to 50 mSv and very high exposure means >50 mSv

About the author: Dr K K Aggarwal is Padmashri and Dr B C Roy National Awardee, President Heart Care Foundation of India, Dean Board of Medical Education Moolchand Medcity, Sr. Physician & Cardiologist, Visiting professor Clinical Research DIPSAR, Past President Delhi Medical Association, Past Academic and Research Wing Head IMA, Chairman Ethics Committee Delhi Medical Council.  

Ask Dr KK: How is radiation measured?

Effective dose of radiation is measured in sieverts (Sv) or millisieverts (mSv). A whole body radiation dose of 1 Sv is associated with a 4 to 5 percent increased relative risk of fatal cancer. (1 Sv = 1000 mSv).

About the author: Dr K K Aggarwal is Padmashri and Dr B C Roy National Awardee, President Heart Care Foundation of India, Dean Board of Medical Education Moolchand Medcity, Sr. Physician & Cardiologist, Visiting professor Clinical Research DIPSAR, Past President Delhi Medical Association, Past Academic and Research Wing Head IMA, Chairman Ethics Committee Delhi Medical Council.  

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Ask Dr KK: How long it takes for the X Ray radiations to harm the health?

 At doses used in diagnostic and interventional procedures, ionizing radiation releases free radicals that may cause DNA damage. This radiation-induced cancers may develop decades after exposure, and include myeloma, blood cancers, lung cancer, thyroid cancer, breast cancer, bone cancer, and skin cancer.

About the author: Dr K K Aggarwal is Padmashri and Dr B C Roy National Awardee, President Heart Care Foundation of India, Dean Board of Medical Education Moolchand Medcity, Sr. Physician & Cardiologist, Visiting professor Clinical Research DIPSAR, Past President Delhi Medical Association, Past Academic and Research Wing Head IMA, Chairman Ethics Committee Delhi Medical Council.  

Ask Dr KK:How safe is angiography radiation?

The mean duration of fluoroscopy in electro physiologic cardiac interventional procedures ranges from 15 to 67 minutes. The radiation dose from one hour of fluoroscopy during electro physiologic ablation procedures can result in 0.7 to 1.4 excess fatal malignancies per 1000 women and 1.0 to 2.6 per 1000 men as per two studies published in American Journal of Cardiology (1998) and Circulation (2004)

About the author: Dr K K Aggarwal is Padmashri and Dr B C Roy National Awardee, President Heart Care Foundation of India, Dean Board of Medical Education Moolchand Medcity, Sr. Physician & Cardiologist, Visiting professor Clinical Research DIPSAR, Past President Delhi Medical Association, Past Academic and Research Wing Head IMA, Chairman Ethics Committee Delhi Medical Council. 

Ask Dr KK:How safe is angiography radiation?

One should not opt for imaging studies unless it is a must; they are not safe and can cause cancers in long run.

A UK analysis published in the Journal Lancet in 2004 had shown that fluoroscopic X Ray radiation exposure during catheter-based coronary angiography can cause up to 280 cases of cancer per million examinations performed.

About the author: Dr K K Aggarwal is Padmashri and Dr B C Roy National Awardee, President Heart Care Foundation of India, Dean Board of Medical Education Moolchand Medcity, Sr. Physician & Cardiologist, Visiting professor Clinical Research DIPSAR, Past President Delhi Medical Association, Past Academic and Research Wing Head IMA, Chairman Ethics Committee Delhi Medical Council.  

Avoid cardiac catheter based imaging procedures if not a must

One should not opt for imaging studies unless it is a must; they are not safe and can cause cancers in long run.

A UK analysis published in the Journal Lancet in 2004 had shown that fluoroscopic X Ray radiation exposure during catheter-based coronary angiography can cause up to 280 cases of cancer per million examinations performed.

The mean duration of fluoroscopy in electro physiologic cardiac interventional procedures ranges from 15 to 67 minutes. The radiation dose from one hour of fluoroscopy during electro physiologic ablation procedures can result in 0.7 to 1.4 excess fatal malignancies per 1000 women and 1.0 to 2.6 per 1000 men as per two studies published in American Journal of Cardiology (1998) and Circulation (2004)

 At doses used in diagnostic and interventional procedures, ionizing radiation releases free radicals that may cause DNA damage. This radiation-induced cancers may develop decades after exposure, and include myeloma, blood cancers, lung cancer, thyroid cancer, breast cancer, bone cancer, and skin cancer.

Effective dose of radiation is measured in sieverts (Sv) or millisieverts (mSv). A whole body radiation dose of 1 Sv is associated with a 4 to 5 percent increased relative risk of fatal cancer. (1 Sv = 1000 mSv).

Mild exposure is called when the exposure is < 3 mSv, Moderate >3 to 20 mSv, High 20 to 50 mSv and very high exposure means >50 mSv.

The effective dose related to any radiologic procedure can be considered in the context of the annual effective dose to individuals from natural background radiation sources, including radon, cosmic rays, terrestrial, and internal sources. This background effective dose, approximately 3 mSv, does not pose a significant risk of future cancer to individuals.

A typical X ray procedure results in a total effective dose of 8.3 mSv per hour of fluoroscopy.  The mean cardiac fluoroscopy time in managing paroxysmal atrial fibrillation is 57 minutes, atrial flutter is 20 minutes, ablation is 22 minutes and Pulmonary Vein isolation is 39 minutes.

Multiple medical tests involving radiation exposure lead to high cumulative doses of radiation. In one study in 20 year period a heart patient may end up with 15 procedures involving radiation exposure. Of these four may be high dose procedures (≥3 mSv). The cumulative estimated effective dose from all medical sources exceeds 100 mSv in 31.4 percent of patients.

Use of CT may account for 1.5 to 2 percent of all future cancers in the United States.

The 2006 Biological Effects of Ionizing Radiation VII lifetime attributable cancer risk model predicts that 1 in 1000 persons exposed to 10 mSv (single diagnostic CT scan of the neck, chest, abdomen, or pelvis) will develop cancer due to that single exposure.

The lifetime attributable cancer mortality risk attributable to a single radiation exposure in a one year-old child is 1 in 550 following an abdominal CT and 1 in 1500 following a brain CT.

It has been estimated that 29,000 future cancers could be attributed to CT scans performed in the US in 2007 alone.

1 in 500 women and 1 in 660 men will develop cancer from their abdominal CT scan if the procedure is performed at the age of 20.

A 45 year-old adult undergoing one single full-body CT procedure would accrue an additional lifetime attributable cancer mortality risk of 0.08 percent from a single scan.

The lifetime attributable cancer mortality risk is 1.9 percent lifetime for thirty years of annual scans.

All patients should be given a general idea about the magnitude of the proposed radiation dose. The exposure should be compared with an estimated effective dose to a single chest x-ray (0.02 mSv), a transcontinental airplane flight (0.02 mSv), or annual individual radiation dose from the natural background (3.0 mSv).

The dose from a single abdominal CT scan is comparable to the collective dose of 400 chest x-rays or natural background radiation for three years.