FAQ's for Physicians

What is Coronary artery disease?
Coronary artery disease involves progressive narrowing within the walls of the blood vessels due to formation of plaques. This process is known as atherosclerosis and is associated with high levels of cholesterol. This can lead to ischemia (lack of oxygen) to the heart muscles resulting in chest pain (angina) or heart attack (infarction).

What is the Coronary artery disease prevalence in India?
Coronary artery diseases will take epidemic proportion by 2015 in our country. Half of deaths in India are likely to be caused by CAD. It will overtake infectious diseases as most common cause of disease in the country. We are predisposed to the disease six times more than the West and 20 times than the Chinese. Specific risk factors for Indians are abdominal obesity, uncontrolled diabetes, insulin resistance, high triglyceride, low HDL cholesterol, high blood pressure and smoking (metabolic syndrome).More alarming is the onset of disease among young Indians.

How is Coronary Artery Disease evaluated?
Traditional coronary angiography takes about 30 minutes to perform and involves hospitalization. It is an invasive procedure which involves catheterization using radial or femoral artery puncture. With CT coronary angiography, the scan takes just a few seconds without the need for hospitalization. It is an outpatient procedure done like any other routine CT scan, using intravenous contrast injection.

What is Calcium Scoring?
Calcium scoring is a technique where the calcification in the coronary arteries is measured and scored. The extent of calcium in the coronary arteries is directly co-related with the risk of a future cardiac arrest. Higher the calcium score, higher is the chances of heart disease. Calcium scoring is also done as a separate test, but since it is very effective in assessing the coronary arteries, it is done as an initial part of the Cardiac CT examination itself.

Advantages of Coronary CTA:

• Quick and non-invasive , with high negative predictive rate.
• Can give accurate and unique information of the coronary arteries including percentage narrowing, type and extent of plaque.
• It is the most sensitive test in detection of coronary artery disease other than intra-vascular ultrasound (IVUS), which requires invasive catheterization of each vessel to its periphery with all of its inherent risks. CTA can non-invasively exclude coronary artery disease.
• Can also simultaneously visualize the pulmonary and systemic arteries of the chest, thereby excluding other dangerous causes of chest pain including pulmonary embolism and aortic dissection. This is otherwise known as a ‘triple rule out study’.

Disadvantages of Coronary CTA:

• Involves radiation exposure – but the dose is significantly low (1-5mSv), using the new snapshot ( prospective ECG gating ) technique – ref. above for details.
• Has difficulty in patients with fast and particularly irregular heart beats. The images can suffer from registration artifacts and blurring.
• It can be difficult and occasionally impossible to quantify the degree of luminal narrowing in heavily calcified vessels

Patient selection protocol for Coronary CT angiogram.