Largely Ignored Type of Cholesterol Linked to Increased Heart Attack Risk

We’ve all heard of “good cholesterol” and “bad cholesterol,” but a different and most often overlooked type of cholesterol also can cause an increased risk of heart attack, even though researchers are not exactly sure why.

Lipoprotein(a) is not as widely tested for as low-density lipoprotein (LDL) or high-density lipoprotein (HDL), even though a new Danish study published in the current issue of the Journal of the American Medical Association suggests the form of cholesterol can be deadly.

Lipoprotein(a) is also called Lp(a) and is made up of LDL cholesterol that is attached to the protein apolipoprotein(a). Because Lp(a) levels can vary greatly from person to person and some people are more predisposed to have higher amounts of the compound than others, the form of cholesterol has not attracted as much attention as the other types, which are more commonly associated with heart disease and other life-threatening complications.

Link Between Lp(a) and Heart Disease

Researchers looking into the role of Lp(a) in causing increased heart risks examined genetic variations in the gene that controls levels of the cholesterol in about 45,000 patients. They found that as levels of Lp(a) rose, so did the risks of heart attacks.

“These findings are consistent with a causal association of elevated lipoprotein(a) levels with increased (heart attack) risk,” said study co-author Borge Nordestgaard.

However, researchers admit they are not sure how Lp(a) increases heart attack risks and said a larger trial to target the form of cholesterol is needed to refine their findings.

Another complication is that treating increased Lp(a) levels is not so easy. Statin drugs have proven effective at lowering LDL and HDL, but the class of cholesterol-fighting drugs is not a proven remedy to Lp(a). A prescription-strength dose of niacin, a B vitamin, is the only treatment linked to specifically lowering Lp(a) levels.

‘Quite Limited’ Risk of Injury

Other researchers say the risk of Lp(a) is “quite limited” and that in terms of lifelong cardiovascular risk, LDL remains a far more dangerous form of cholesterol than Lp(a). High-blood pressure and levels of LDL and HDL are still the best indicators of heart attack risk, researchers said.

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