Are there accurate ways to predict the likelihood that you will have, or die from, a heart attack or stroke in the near future?

Quite a few "biomarkers," or predictors, of these dire events have been discovered. But how helpful are these tests? You shouldn't have to pay for tests you may not really need.

Researchers examined 10 of these biomarkers in more than 3,000 participants in the long-term Framingham Heart Study to see which ones were most useful. The following five were found to do the best job of predicting the risk of death from heart attack or stroke during 7.4 years of follow-up.

• C-reactive protein (CRP). Surprisingly, the blood test for C-reactive protein (CRP) predicts the risk of death, but not of cardiovascular events.
• Homocysteine. Homocysteine is an amino acid produced in the body in higher amounts when levels of the vitamin folic acid are low.
• B-type natriuretic peptide. This peptide is one of the most effective individual markers to predict both the risk of cardiovascular events and death.
• Renin. An enzyme produced and released by the kidneys into the bloodstream to regulate blood pressure.
• Urine test measuring the ratio of albumin to creatinine. Like the B-type natriuretic peptide, this marker predicts both the risk of cardiovascular events and of death.

Five other blood biomarkers tested in the study were less useful:

• Fibrinogen. A protein converted to fibrin to form a major component of blood clots.
• Plasminogen-activator inhibitor. This substance hinders the body's ability to produce plasmin, an enzyme that helps to eliminate blood clots. Thus, it interferes with the removal of blood clots formed in arteries. 
• D-dimer. A breakdown product of fibrin, D-dimer is a marker of blood-clot formation that can predict the likelihood of a heart attack.
• Aldosterone. A hormone secreted by the adrenal cortex that raises blood pressure by increasing sodium retention by the kidney.
• N-terminal pro-atrial natriuretic peptide. This peptide is released from the atria of the heart in response to increased blood pressure. It is a predictor of total and cardiac death in survivors of a previous heart attack.

As you might expect, the Framingham analysis found that people who had high levels of multiple markers were at a significantly greater risk of heart attack and stroke, and especially a greater risk of death. Here are some points to remember about even the more sensitive of these newer biomarkers:

• Testing for them added only a little to the information already provided by the standard tests currently used to assess the risk of cardiovascular events (high LDL cholesterol, high blood pressure, cigarette smoking, low HDL cholesterol, diabetes, family history, and age).
• These markers should be used only, if at all, in those people found to be at "intermediate risk," based on the standard risk factors. (But since most Americans fall into the intermediate-risk category, my guess is that certain of these newer tests will continue to be widely used.)

If you have been told to obtain one or more of these biomarker tests, ask your doctor why. And also, before you ask your doctor for a biomarker test that you heard about from a friend or newspaper story, always first ask whether your level of risk warrants getting it.