Harvard Heart Letter

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.

To continue reading this article, you must login.
  • Research health conditions
  • Check your symptoms
  • Prepare for a doctor's visit or test
  • Find the best treatments and procedures for you
  • Explore options for better nutrition and exercise
Learn more about the many benefits and features of joining Harvard Health Online »