Heart attack despite low cholesterol?
Ask the doctor
Q I have a relative who had a total cholesterol value of 155, yet he still had a heart attack with 90% blockage in one artery. How could that happen?
A I understand your confusion, considering how doctors have long focused on the importance of having an optimal total cholesterol level (less than 200 milligrams per deciliter or mg/dL) as a way to lower the chance of having a heart attack. It's actually the harmful LDL cholesterol value that's most important in terms of this risk. However, a person with a total cholesterol level of 155 mg/dL probably has an LDL level under 100 mg/dL, which is currently considered a reasonable target for avoiding heart disease.
In a population, a lower LDL level is—on average—associated with a lower risk of heart attack. But about half of all heart attacks occur in people with "normal" cholesterol levels. An individual person may have a whole range of other conditions that could raise the risk. Some of the best-known ones are smoking, diabetes, high blood pressure, obesity, and a lack of physical activity. Other potential contributors include secondhand smoke and air pollution. In addition, there are likely genetic and lifestyle factors that we don't fully understand.