It is known that there are at least 16 different types of CT scanners available nowadays in public and private hospitals. But doctors do caution that while these scanners promise a clear picture of the heart through non-invasive technology, they are not suitable for all heart disease patients.

According to one cardiologist, "people with heart-related symptoms like chest pain or shortness of breath and who have got abnormal or unclear results from stress test will benefit from these cardiac CT scans."

Cardiac CT uses X-ray imaging to take images of the heart timed to the heartbeats to avoid motion blurring. It can provide information about the extent of blockages by detecting the amount of plaque build-up in the arteries. Compared with invasive angiography, the CT coronary angiogram is highly accurate.

Electrocardiograms (ECGs) and treadmill tests are not very useful for preventing heart attacks, pointed out by another heart specialist. Published studies show that two-thirds of heart attacks occur in patients with 40 to 60 percent narrowing of arteries, yet this is not picked up on treadmill tests or ECG.

He admitted that cardiac CT has done away the need for invasive coronary angiograms in his practice. His many years of experience indicate that once patients see that their scans show blockages, they usually opt to start on medication right away. A trial of more that 2000 stable heart patients completed in 2006 in the United States showed that patients do just as well on aggressive drug therapy alone as they do with angioplasty thrown in.

Medical therapy is not inferior to stenting. Stents are just devices that are put inside blood vessels during angioplasty to keep vessels from narrowing again. Thus, invasive procedures can be prevented.

Nevertheless, risks and certain side effects do arise from using cardiac CT scans.

For example, the contrast dye injected into a patient may cause an allergic reaction, but this is rare. It can also compromise kidney function for people who have kidney problems. Moreover, the exposure to radiation is found to be equivalent to 600 chest X-rays. However, technology is improving and a new dual-source CT scanner which takes X-ray images faster than from a single source does reduce the radiation that a patient is exposed to by 50 to 70 percent.