Harvard Heart Letter

HDL and heart attack

High LDL cholesterol levels are known to increase the risk of heart attack, and lowering LDL levels has been proven to help protect against heart attack. Conversely, high levels of HDL cholesterol tend to be associated with a lower risk of heart attack. Yet clinical trials have not shown that people with genetically high HDL cholesterol levels have a lower risk of coronary artery disease. Therefore, it has been unclear whether raising HDL cholesterol levels would lower the risk of heart attack. Under the direction of Dr. Sekar Kathiresan, director of preventive cardiology at ?Harvard--affiliated Massachusetts General Hospital, a large group of international researchers undertook a complex genetic study to find the answer. First, they tested individual genetic variants for LDL cholesterol to determine their association with heart attack, and found a consistent association. But a genetic variant that substantially increases plasma HDL cholesterol did not reduce the risk of heart attack, nor did the combination of 14 variants exclusively related to HDL cholesterol. This calls into question whether raising HDL cholesterol with a drug or other measure would reduce the risk of heart attack. Ongoing studies are addressing this issue.

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