The new study, which is an analysis of 20 past studies involving nearly 21,000 heart attack cases, found that though keeping low-density lipoprotein or LDL (also known as bad cholesterol) under check is good for the heart, raising levels of HDL may not have any impact on one's heart disease risk.
The study, published in The Lancet, showed that people with a genetically-programmed tendency for higher HDL cholesterol concentrations didn't have a lower susceptibility to heart attack.
"These results show that some ways of raising HDL cholesterol might not reduce risk of myocardial infarction (heart attack) in human beings," said lead study author Sekar Kathiresan of Massachusetts General Hospital, Broad Institute, and Harvard Medical School in the US.
"Therefore, if an intervention such as a drug raises HDL cholesterol, we cannot automatically assume that risk of myocardial infarction will be reduced," Kathiresan explained.
HDL cholesterol is known as "good" cholesterol because higher concentrations have been associated with lower risk of heart attacks in observational studies, but whether this association is causal is uncertain.
While lowering low-density lipoprotein or LDL, or "bad", cholesterol decreases the risk of heart attack, it has not been shown that raising HDL similarly reduces the risk of heart attack.
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In the new study, the researchers compared heart attack risks in people with an inherited increase in HDL cholesterol (those carrying the LIPG 396Ser allele) who would be expected to have a reduced risk of heart attack.
Their analysis, which involved 20,913 heart attack cases and 95,407 controls from 20 studies, showed that people with LIPG 396Ser allele did not have a lower susceptibility to heart attack.
The researchers then constructed a genetic risk score testing for 14 common genetic variants exclusively associated with HDL cholesterol in nearly 12,500 people with a history of heart attack and over 41,000 controls. (More)