1. Coronary Angiography (CAG) is the gold standard for identifying the blocked coronary arteries. This method provides the most accurate result.   

Advantage: 

• Proper treatment can be immediately performed by balloon angioplasty or percutaneous coronary intervention (PCI).

Disadvantage: 

• It poses some risk for complications, e.g. dissection, because the catheter has to be inserted into an artery from a patient’s groin or arm or wrist to be carefully threaded to coronary arteries. However, such risk is very slight under the expert treatment of qualified doctors.
• It is quite costly.
• Patient needs to remain in hospital for 4-24 hours after the procedure.

2. Coronary Computed Tomographic Angiography (Coronary CTA)

CT technology has been rapidly evolving over the past several years. It now provides a high-resolution and high-contrast image of a small and beating organ such as the heart.
 
Patients undergoing a Coronary CTA scan receive an iodine-containing contrast dye as an intravenous solution to ensure the best images possible. During the examination, this usually takes about 10 minutes, x-rays pass through the body and are picked up by special detectors in the scanner.

 

Advantage:

• MDCT (Multi-Detector Computerized Tomography) procedure can be performed in a short time.
• Patient is not required to stay in hospital after the procedure.
• It delivers a high accuracy of over 90% in detecting coronary artery disease.

Disadvantage:

• It takes around 1-2 hours for image processing after the actual scan.
• Patient must have a regular heart rate and can hold the breath for about 10 seconds for each scanning with the newer generation of CT scanner. These requirements become unnecessary.