An Example of Estimating The Risk of A Coronary Artery Bypass Graft Surgery In a Patient With Stable Coronary Artery Disease (also called Stable Ischemic Heart Disease–SIHD)

Here is an example of how we estimate the risk of Coronary Artery Bypass Surgery (CABG) in a specific patient.


The patient is a 60 year old man who has stable angina. That means he gets chest pain when he exercises at a certain intensity or experiences strong emotion.

He has had a coronary angiogram which showed severe blockage in all three of his coronary arteries (right coronary, left anterior descending, and left circumflex) near where each begins. In addition, he has a 60% narrowing of the left main coronary artery (the heart artery that gives rise to the left anterior descending and to the left circumflex).

The doctor and patient review a summary of the guidelines on CABG and coronary angioplasty/stent (PCI which stands for Percutaneous Coronary Intervention) available at:

Both agree that the patient has severe coronary artery disease and that coronary artery bypass graft surgery is indicated to improve the patient’s chances of survival.

So now the patient would like to know the risk of the heart surgery. They go to the Society of Thoracic Surgeons Risk Score Calculator at:

There they fill in the form which is basically a complete medical history and when they are done they receive a series of estimates about the risks of the surgery. In the example my patient is a 60 year old man with no history of heart attack or of previous CABG or PCI.

When I filled in the form, the calculator found that the patient’s risk of dying from the surgery is estimated to be 0.3%. The risks of all the other possible complications of the surgery are also listed on the form.

The doctor and patient believe that the risk estimates are reasonable and the patient decides to go ahead with the surgery.

Go ahead and take a look at the STS Risk Score Calculator. You can make up your own patient to fill in the form. Again, it is at


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