(Reuters) - Updated U.S. guidelines on heart health advise more personalized assessment of risk as well as two newer types of cholesterol-lowering drugs for people at particularly high risk of heart attack or stroke.

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The recommendations from the American Heart Association and the American College of Cardiology, last issued in 2013, acknowledge recent research showing the benefit of very low levels of “bad” LDL cholesterol, which contributes to fatty plaque buildup and narrowing of arteries.

The medical groups, which announced the guidelines on Saturday at the AHA’s annual meeting in Chicago, still emphasize a healthy diet and exercise as the first line of defense against heart disease, the No. 1 killer in the country.

When cholesterol is not controlled by lifestyle efforts, patients are typically prescribed statin drugs, available as low cost generic pills that have long been proven to safely and effectively lower LDL levels and heart disease risk.

For people who have had a heart attack or stroke, are at high risk for another and whose cholesterol levels are not adequately lowered by statins, the guidelines now recommend adding newer cholesterol drugs.

Higher risk patients are advised to first try statins in combination with ezetimibe, the generic version of Zetia, which lowers cholesterol by limiting its absorption from the intestine. If that does not work, the guidelines call for newer injected medications known as PCSK9 inhibitors, specifically for people who are at very high risk or who have a genetic condition that causes very high cholesterol levels.

Two PCSK9 drugs - Amgen Inc's AMGN.O Repatha and Praluent from partners Regeneron Pharmaceuticals Inc REGN.O and Sanofi SA SASY.PA - were launched in 2015 at U.S. prices of over $14,000 a year.

Both have been shown to dramatically lower cholesterol levels, but uptake as been slow as the medical community and health insurers questioned their cost effectiveness.

To help spur usage, Amgen last month cut Repatha’s list price by 60 percent to $5,850 and Praluent’s annual net price was cut earlier this year to between $4,500 and $6,600.

The new guidelines are fairly “conservative” in recommending that the newer drugs be used only after other options, said Dr. Francisco Lopez-Jimenez, a cardiologist at the Mayo Clinic in Rochester, Minnesota, adding “I think that was the right approach.”

The guidelines continue to include a calculator introduced in 2013 to identify a patient’s 10-year risk for cardiovascular disease. In addition to traditional risk factors such as smoking and high blood pressure, doctors are now urged to discuss family history and ethnicity as well as health conditions such as chronic kidney disease and premature menopause.

They are also advised to test for cholesterol levels in children as young as two with a family history of heart disease or high cholesterol, while other children should have an initial test between the ages of nine and 11.

Coronary artery calcium measurements are advised for people whose risk level is not clear.

The guidelines update has more specific recommendations for certain age and ethnic groups, as well as for people with diabetes.