Assessing Risk of Developing Heart Artery Disease

• Major risk factors
• Are additional tests helpful as a checkup if one has not had a heart attack or angina?
• CT calcium scores- can be helpful as part of a routine checkup.
• Questions that can arise after a family member has an unexpected heart attack.
• Heart artery disease in families

CT Coronary Calcium Scoring

Calcium is deposited in the arteries as people get older. More calcium is present in the arteries of persons with heart artery disease. There is a relationship between the amount of calcium in the arteries and the future risk of heart attack.

The amount of calcium in the arteries can be assessed with X-rays obtained with a special CT scanning machine.

Should all persons have a CT Coronary Calcium Score?

The precise role of this technology is a matter of debate. There is information to suggest that this test can be useful in persons that are assessed as being at "moderate risk" of future heart artery problems, such as angina and heart attack.

The test is likely to have an important role in the assessment of some persons.

Assessment of Risk Factors

An estimate of future risk of heart artery problems can be obtained from the assessment of traditional risk factors.

Guidelines recommend that those at "high risk" should have a lower threshold to use drugs to improve the risk factor levels to reduce the risk of heart attack and angina.

Unfortunately, a small proportion of patients' risk of future problems is incorrectly assessed on the basis of their risk factor status. For example, after measurement of risk factors we might assess a person to be at "moderate" risk, when their risk of future events is "high".

A more correct assessment of "high risk" status would allow us to recommend medication to improve blood pressure and cholesterol levels and on the use of low dose Aspirin.

CT Calcium Scoring Helpful in "Moderate-Risk" Male Patients

Those that might have a five to ten percent chance of a heart attack or stroke in the subsequent five years may be candidates for further testing. If the CT calcium score is high than these persons will also be eligible to use drugs to improve their cholesterol and blood pressure levels to help reduce risk of future events. The alternative of treating all with drugs is expensive and also will not be acceptable to all persons.

How Useful is CT Calcium Scoring in "Moderate-Risk" Patients?

The Dallas Heart Study found that one in fifteen men that were at "moderate-risk", using risk factor assessment, were actually at "high risk" using CT calcium scoring.

One in fiften men aged between thirty and sixty-five years were at higher risk than indicated after assessment using the established risk factor approach.

This study also found that another one in fifteen men that might be considered to be at "low-risk" were also incorrectly assigned using the risk factor approach.

Limitations of CT Calcium Screening

In the Dallas Heart Study, female patients between the age of thirty and sixty-five years were less likely to get useful information from CT Calcium Scoring. This suggests we need to be more selective when recommending this test to women.

Despite its limitations, the test may well be superior to treadmill stress testing in some groups.

CT Calcium Scoring is a new technology. There are many unanswered questions. A very low CT Calcium Score should be reassuring but no persons can ever be informed that they have a nil risk of future heart artery disease.

At this time, the test is not available in the public hospital sector in New Zealand, but can be performed in the private sector. The test may not be funded by Health Insurance Companies.

Dr Hitesh Patel, Cardiologist
April, 2007